Read this excerpt from "Why Are They Called Black Holes?" After many millions or billions of years, the star runs out of hydrogen and energy. Then the star "dies" and collapses into a dense little ball with tons of gravity. Albert Einstein’s theory of relativity predicted that black holes would have to exist if a dead star had enough gravity. Using Einstein's theory, astronomers calculated that if a star more than three times as heavy as our sun died, the force of gravity pulling matter in could overwhelm any other force pushing matter out.

ON A EXAM PLEASE HURRY

In this excerpt, the author makes a connection between a scientific theory and

the calculations that scientists make.
the beginning of a star's existence.
the idea that all things live and die.
the question of why gravity exists.

Why it's time to lay the stereotype of the 'teen brain’ to rest 2. part b: which detail from the text best supports the answer to part a? a “brain deficits don’t make teens do risky things; lack of experience and a drive to explore the world are the real factors.” (paragraph 1) b “according to this theory, the prefrontal cortex, the center of the brain’s cognitive-control system, matures more slowly than the limbic system, which governs desires and appetites including drives for food and sex.” (paragraph 5) c “in experiments that mimic the well-known marshmallow test, in which waiting for a bigger reward is a sign of self-control, adolescents are less impulsive than children and only slightly more so than adults.” (paragraph 12) d “the majority of adolescents do not die in car crashes, become victims of homicide or suicide, experience major depression, become addicted to drugs or contract sexually transmitted infections.” (paragraph 14)