Giant Molecular Clouds, Which Are Major Sites of Star Formation

Giant molecular clouds, which are major sites of star formation, can be up to about

A) 10 times the size of the solar system and contain 2 to 3 solar masses of material.
B) 10 pc across and contain a few thousand solar masses of material.
C) 100 pc across and contain 2 million solar masses of material.
D) 1000 pc across and contain 100 million solar masses of material.