Here, we have to emphatically focus attention on the grammatical correctness of the statement so as to be able to make a wise decision.

Option A - INCORRECT
We would have noticed how grammatically incorrect statement in A is especially the improper usage of the verb "builds" in a past tense format. Absolutely wrong.

Option B - INCORRECT
We have that a disjointed statement with no grammatical credibility whatsoever. Is it wrong to use the future tense "will" in a statement that has the past participle object "have been".

Option C - CORRECT
This aptly explains the tense usage in all forms. Present continuous verb "building" is a right choice of words here and makes it more correct than all other options so far considered.

Option D - INCORRECT
This bears enough semblance when compared with the option C above only that it falls short of explanation.The difference is the object verb "to do" which simplifies the context more in the previous option statement.

Option E - INCORRECT
This is an over-specified statement. In "recent times" as used herein connotes a different meaning when compared with "recently" while one shows the "past" the second shows continuity.