Which verb tense fits better in my sentence?

[hardworker]

I would like to make up a sentence.

(ex) From its grand opening to four months later, the computer company ____ its revenues by thirty percent.

(a) increased
(b) has increased
(c) has been increasing


I am not sure which verb form is correct in this sentence. Please explain it. Thanks a lot.

[knowable]

Since its grand opening four months ago, the computer company has increased its revenue by thirty percent.
Here I am talking about an event in the present.

Four months after grand opening, the computer company increased its revenue by thirty percent.
Here I am talking about an event in the past.