Answer: the evidence that supports the formation of a single elliptical galaxy by collision of spiral galaxies are:
A) at the core of dense clutters of galaxies, elliptical galaxies are populous in the galaxy populations.
B) observations of some elliptical galaxies with stars and gas clouds in their cores that orbit differently from the other stars in the galaxy.
C) observations of shells of stars revolving around elliptical galaxies that may have formed from stars that have been stripped of from smaller galaxies.
D) observations that show that at the center of dense clusters, giant elliptical galaxies may have grown by consuming other galaxies.
Step-by-step explanation:
Elliptical galaxies contain older stars and less gas. The universe is a violent place, and collisions between galaxies are frequent, hence when two spirals collide, they lose their familiar shape, morphing into the less-structured elliptical galaxies.