What Is Believed to Prevent Stars from Being Larger Than

What is believed to prevent stars from being larger than a few hundred solar masses?

A) Stars of larger mass would collapse under their own gravity and become black holes.
B) No interstellar clouds have masses of more than 100 solar masses.
C) The cores of larger-mass stars would run through their lives and explode before the stars finish contracting as protostars.
D) The temperature becomes so high that the excess mass is pushed back into space by radiation from the star.