Why Is It So Difficult for Astronomers to See New

Why is it so difficult for astronomers to see new stars in the process of birth?

A) birth happens very quickly, so it is hard to "catch" stars "in the act"
B) most stars are born inside dusty clouds, which block any light that may be coming from the stars
C) the size of a newly forming star is typically quite small and thus hard to make out
D) protostars which are not yet doing fusion do not give off a lot of visible light
E) all of the above