Answer:
b. The universe may continue to expand.
Step-by-step explanation:
The most supported theory about the future of the universe is that, it may continue to expand up to such point that it will become too cold to allow any forms of life to pull through. This is popularly known as the "Big Freeze."
Such acceleration of expansion is caused by the so-called, "dark energy." This also explains why the acceleration of expansion is not constant. This thereby causes the distance between galaxies to grow farther apart.