"...star formation begins when part of the interstellar medium--one of the cold, dark clouds... starts to collapse under its own weight. The cloud fragment heats up as it shrinks, and eventually its center becomes hot enough for nuclear burning to begin. At that point, the contraction stops, and a star is born."
The answer would be "A." Simply listing traits, like short or blue-eyed, would not help you understand your mental framework as much as the other options would.
