Sentence Correction

1) In population genetics, the term "genetic drfit" refers to the process by which gene frequencies in a population change from one generation to the next as the result of random chance.

a) by which gene frequencies in a population change
b) by which gene frequencies in a population have been changed
c) that gene frequencies in a population change
d) of gene frequencies in a population have been changing
e) of the change of gene frequencies in a population

Correct answer is A, but I would like to understand correct usage of BY WHICH. Can anyone throw some light on appropriate usage and meaning of BY WHICH.

Why A is incorrect in the following SC:

2) The agreement, the first to formally require industrialized countries to cut emissions of gases linked to global warming, is a formal protocol by which 38 industrialized countries must reduce emissions of these gases by 2012 or face heavy penalties.

A) by which

B) for which

C) under which

D) such that

E) wherein

Source: [spoiler](1) Veritas; (2) GMATPREP; [/spoiler] OA-C

My understanding:

The process changes the gene frequencies. Hence we use the process by which gene frequencies change.

I think here we can use through which also.

In the second eg, the protocol doesn't directly reduce the emissions. Protocol mandates the reductions, hence we use under which.

For first, A looks concise and correct !

For second, Under looks good to me !

You have to first understand how preposition + relative pronoun is derived, then I think these two questions will be a easy one.

clause 1 - The students play in the park.
clause 2 - Government ordered the renovation of the park.

combine both the clause : government ordered the renovation of the park in which the students play.

Applying this here :

1. the term "genetic drfit" refers to the process.
gene frequencies in a population change from one generation to the next as the result of random chance by a process.

this two sentence is quiet logical and hence "by which" is correct.


2. the agreement is a formal protocol.
38 countries do XXXXX ..... under a formal protocol.

yes --- logical "under which" is correct. the correct one is C - please share the OA for the 2nd one ?

hope this helps!!

Can someone please explain me why E is not correct in the first question

confuse mind wrote:Can someone please explain me why E is not correct in the first question

I'm not sure but E just doesn't sound right and changes the meaning of the sentence.
Pretty awkward I must say.