Critical Reasoning

Tiger sharks are common in the waters surrounding Tenare Island. Usually tiger sharks feed on smaller sharks, but sometimes have attacked tourists swimming and surfing at Tenare's beachs. This has hurt Tenare's tourism industry, which is second only to its fishing industry in anual revenues. In order to help the economy, therefore, the mayor of the island has proposed an ongoing program to kill any tiger sharks within a mile of the beaches.
Which of the following, if true, most strongly calls into question the likelihood that implementation of the mayor's proposal will have the desired consequences?

a) Even if not all the tiger sharks that come close to the beaches are killed, the existence of the program would reassure the tourists.

b) business owners who depend on tourism will pay most of the cost of impelemting the program.

c) Tourists come to Tenare Island for its beaches, even though the island features a number of other tourist attractions.

d) The small sharks on which tiger sharks prey feed on fish that are commercially important to the island's fisheries.

e) Not all tourists who come to Tenare Island enjoy swimming or surfing.

Yhe corect and is D and i chose B because If the business owners have to pay for most of the cost of implementing the program, then the plan to help the economy will not work... Please explain to me why my reasoning is wrong.

The goal of the plan is to help the island's economy.

We know the economy has 2 main components: fishing and tourism.

The mayor's plan is designed to boost tourism. In order for the plan to boost the entire economy, the mayor has to be assuming that the plan won't adversely affect the other sector, fishing.

Since the mayor's plan is to kill off a bunch of fish, we can predict that a good way to weaken the plan would be to show that the plan will negatively impact the island's fishing revenues.

Scanning the choices, only (d) even talks about the fishing industry, so we should choose it even if we don't 100% understand it.

Thinking about (d), we have a food chain:

tiger sharks eat small sharks which eat commercial fish.

If we were to kill off all the tiger sharks, then there would be more small sharks eating the tasty fish, which would negatively impact the fishing industry: yep, (d) weakens, choose (d).

(b) doesn't give us enough information to determine what impact it will have on the overall economy. If the cost of the program is a small fraction of the extra revenues that these businesses would earn, then (b) is irrelevant. If the cost of the program is a large multiple of the extra revenues that these businesses would earn, then (b) would weaken. Anytime you look at an answer choice and are faced with a quesion to which you don't know the answer (in this case "what will the payoff be for the extra money spent on the program?"), that choice is outside the scope and can be eliminated.

A good general rule for both CR and RC is "the more work you have to do to justify an answer choice, the LESS likely it is that the choice is correct".

Classic food chain question eh?

"the more work you have to do to justify an answer choice, the LESS likely it is that the choice is correct".

Good method

In my opinion B is the most logical one