Sentence Correction (SC) | Re: Just forty years ago, the idea of any planets outside our Solar System

Just forty years ago, the idea of any planets outside our Solar System was purely speculative, but by now astrophysicists have confirmed the discovery of over 3000 exoplanets throughout the galaxy, although much less of thesefall in the “habitable zone,” where Life is thought to be possible.

A. much less of these fall
B. much less of these had fallen
C. many less of these fall
D. many fewer of these fall
E. many fewer of these hadfallen