Which of the Following Processes Slowed the Collapse of Protogalactic

Which of the following processes slowed the collapse of protogalactic clouds?

A) the formation of the first generation of stars
B) the conversion of gravitational potential energy into kinetic and thermal energy as the cloud collapsed
C) the shock waves from the exploding supernovae of the earliest stars
D) the pull of gravity of the mass of the cloud material
E) the radiating away of thermal energy