A 16th century religious movement that attempted to reform the Roman Catholic Church
The answer here <em>could </em>be either B. or D. But B. is the most correct, given that the question is so general.
Gravity and Heat
"...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."
