What Determines Whether a Particular Region of an Interstellar Cloud

What determines whether a particular region of an interstellar cloud can collapse and form a star?

A) temperature, since higher temperatures act to prevent collapse
B) amount of gravity pulling inward compared with gas pressure pushing outward
C) gas density (the ratio of the mass of the cloud over its volume) , since density determines how gravity will act on the cloud material
D) amount of mass in the cloud, since mass determines the strength of gravity