Sentence Correction

The results of the company's cost-cutting measures
are evident in its profits, which increased 5 percent
during the first 3 months of this year after it fell over
the last two years.
(A) which increased 5 percent during the first
3 months of this year after it fell
(B) which had increased 5 percent during the first
3 months of this year after it had fallen
(C) which have increased 5 percent during the first
3 months of this year after falling
(D) with a 5 percent increase during the first
3 months of this year after falling
(E) with a 5 percent increase during the first
3 months of this year after having fallen


I do not understand the explanation of why options A and B, I mean, why the tenses do not distinguish beetwen times?
A The verb tenses do not distinguish between
the times at which these indicators occurred;
the singular it does not agree with the plural
profits.
B The verb tenses do not distinguish between
the times when the indicators occurred; the
singular it does not agree with the plural
profits.

Thanks in advance,
FM