MAGOOSH OE:
Split #1: the progressive verb is not inappropriate. We don't need to know whether life on some other planet is in the process of developing at some exact instant. That's not the concern of the sentence. The future case in (B) therefore doesn't fit.
Split #2: according to the scientists, the conditions themselves already guarantee that life "could develop". If a planet meets these conditions, there's nothing hypothetical in question --- we know life "could develop." We want to know whether life actually has developed. Both hypothetical answers, (C) & (E), are wrong.
Split #3: The structure in (A) is quite unusual. The structure "is"/"are" + [infinitive] connotes some sort of necessity: an authoritative order or something about destiny. (a) I have never seen the structure employed as part of a correct answer on the GMAT. (b) Its connotations are completely wrong here—nothing is setting the planet's "destiny." This is incorrect.
This development could have happened in the past, up to and including the present: for this, we need the present perfect tense. Only (D) has this. (D) is the only possible answer.