How Does a 15-M ? Star Evolve in the First

How does a 15-M ? star evolve in the first 10⁵ years after it becomes a protostar?

A) Its temperature remains relatively cool at about 4000 K, but its luminosity decreases by a factor of 100.
B) Its brightness and temperature remain approximately constant as it stabilizes into a nuclear-heated star on the main sequence.
C) Its brightness remains constant, while its surface temperature increases by a factor of 10.
D) Its brightness increases by about a factor of 10⁴, because its temperature increases by a factor of 10, moving it upward along the main sequence.