The results of the company's cost-cutting measures are evident in its profits, which increased five percent during the first three months of this year after it fell over the last two years.

A. which increased five percent during the first three months of this year after it fell

B. which had increased five percent during the first three months of this year after it had fallen

C. which have increased five percent during the first three months of this year after falling over the last two years

D. with a five percent increase during the first three months of this year after falling

E. with a five percent increase during the first three months of this year after having fallen


Can anyone explain the meaning shift in a,b and c?
I believe that tense shift can only be correctly learned by understanding the meaning change.

Further, is adverbial phrase "during the first 3 month" has any impact on "tense"?
I believe it has.

I think that "adverbial phrases" for "time"(ie answering "when?") have an impact on the choice of tenses.
please correct me and my understanding.


also, explain meaning change if using "adverbial modifier" as in D and E?

even though i got this answer correct, i still don't understand the exact meaning change in all options.[spoiler]

Source: OG13 Q90
OA: C[/spoiler]