In this kind of questions is useful to pick numbers to prove the answer choice.

Let's say that last year the company had $100 profit

chemical division ---> $60 --->60%
pharmaceutical division --->$20 ---->20%
others ------> $20

This year the company has $45 profit
pharmaceutical division --->$20 ----> 45%
chemical division ---> $15 --->33%
others ------> $10 ---> 22%

what the passage says is that the pharmaceutical division is growing faster, well this is not true since its profits haven't increased.
This is way C is correct. You don't need to assume that the total profits haven't changed, in fact if they don't change the passage is true.

(E) The information cited does not make it possible to compare the performance of the chemical and pharmaceutical divisions in of the percent of total profits attributable to each

this means that you don't have the percentage of the chemical division. Do you need the percentage of the chemical division to conclude that the pharmaceutical division is growing stronger?

the author did not compare the performance but rather said that the pharmaceutical division is growing stronger. It's obvious that the chemical division performed worse that the pharmaceutical division last year but that is not the conclusion of the argument.
+1
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