Critical Reasoning

Please help me in understanding how i was wrong in answering the below questions. I got them all wrong and unable to justify the answers myself. No explanation is given and the questions are from 1000 LSAT CR doc i got.

1.In the years since the city of London imposed strict air-pollution regulations on local industry, the number of bird species seen in and around London has increased dramatically. Similar air-pollution rules should be imposed in other major cities.
Each of the following is an assumption made in the argument above EXCEPT:
(A) In most major cities, air-pollution problems are caused almost entirely by local industry.
(B) Air-pollution regulations on industry have a significant impact on the quality of the air.
(C) The air-pollution problems of other major cities are basically similar to those once suffered by London.
(D) An increase in the number of bird species in and around a city is desirable.
(E) The increased sightings of bird species in and around London reflect an actual increase in the number of species in the area.

OA: A (I answered it as D. I can't understand how local industry isn't an assumption?)

2.In many surveys, American consumers have expressed a willingness to spend up to 10 percent more for products that are ecologically sound. Encouraged by such surveys, Bleach-O Corporation promoted a new laundry detergent, Bleach-O Green, as safer for the environment. Bleach-O Green cost 5 percent more than typical detergents. After one year, Bleach-O Green had failed to capture a significant share of the detergent market and was withdrawn from sale.
Which of the following questions is LEAST likely to be relevant in determining the reasons for the failure of Bleach-O Green?
(A) How effective as a detergent was Bleach-O Green?
(B) How many other detergents on the market were promoted as safe for the environment?
(C) How much more did Bleach-O Green cost to manufacture than ordinary detergents?
(D) To what extent did consumers accept the validity of Bleach-O Green advertised and promoted to consumers?
(E) How effectively was Bleach-O Green advertised and promoted to consumers?

OA: C (I answered it as D. Can someone explain how cost of manufacture is least likely to be considered.)

3.The upcoming presidential election in the West African republic of Ganelon is of grave concern to the U.S. State Department. Ganelon presently has strong political and military ties to the United States. However, the Socialist party is widely expected to win the election, leading to fears that Ganelon will soon break away from the pro-American bloc and adopt a nonaligned or openly anti-American stance.
Which of the following is an assumption made in the passage above?
(A) A Socialist party government in Ganelon is more likely to oppose the United States than is a non-Socialist party government.
(B) The people of the United States recognize their nation's interest in the political stability of West Africa.
(C) A weakening of U.S. political ties with Ganelon could have serious consequences for U.S. relations with other African nations.
(D) The Socialist party leaders in Ganelon believe that their nation's interests would best be served by an alliance with anti-American forces.
(E) The Socialist party will win the upcoming election in Ganelon.

OA: A (I answered it as D. Non-socialist party's view is not needed to be assumed.)

4.No nation can long survive unless its people are united by a common tongue. For proof, we need only consider Canada, which is being torn asunder by conflicts between French-speaking Quebec and the other provinces, which are dominated by English speakers.
Which of the following, if true, most effectively challenges the author's conclusion?
(A) Conflicts over language have led to violent clashes between the Basque-speaking minority in Spain and the Spanish-speaking majority.
(B) Proposals to declare English the official language of the United States have met with resistance from members of Hispanic and other minority groups.
(C) Economic and political differences, along with linguistic ones, have contributed to the provincial conflicts in Canada.
(D) The public of India, in existence sine 1948, has a population that speaks hundreds of different, though related, languages.
(E) Switzerland has survived for nearly a thousand years as a home for speakers of three different languages.

OA: E (Where does it say that switz didn't had a common language or 1000 years was long?)

5.In the effort to fire a Civil Service employee, his or her manager may have to spend up to $100,000 of tax money. Since Civil Service employees know how hard it is to fire them, they tend to loaf. This explains in large part why the government is so inefficient.
It can be properly inferred on the basis of the statements above that the author believes which of the following?
I. Too much job security can have a negative influence on workers.
II. More government workers should be fired.
III. Most government workers are Civil Service employees.
(A) I only
(B) I and III only
(C) II only
(D) I, II, and III
(E) III only
OA: A (I answered it B. The last line in the passage can be related to point III).


6.Ronald: According to my analysis of the national economy, housing prices should not increase during the next six months unless interest rates drop significantly.
Mark: I disagree. One year ago, when interest rates last fell significantly, housing prices did not increase at all.
It can be inferred from the conversation above that Mark has interpreted Ronald's statement to mean that
(A) housing prices will rise only if interest rates fall
(B) if interest rates fall, housing prices must rise
(C) interest rates and housing prices tend to rise and fall together
(D) interest rates are the only significant economic factor affecting housing prices
(E) interest rates are likely to fall significantly in the next six months

OA: B (I am totally lost between A and B.)