It looks like you're new here. If you want to get involved, click one of these buttons!
Correct: A
Incorrect: C
https://7sage.com/lsat_explanations/lsat-53-section-1-question-09/
"C" is incorrect because the male population could've stayed the same and the decline of the female population made it equal to the male population. "A" is correct because "proportional" gives relation to the whole population. It is saying that the decline of the female population is a decline in the total population. This takes it from being 2/3 of just females to 2/3 of the species.