Which of these statements best describes a similarity between the two galaxies?

both have elongated centers.
both have centers shaped like bars.
both change their shape from time to time.
both are held together by gravitational forces.

The correct statement is both are held together by gravitational forces.

Explanation:

Galaxies are defined as the system which contain millions or billions of stars bind together by gas or dust and held together by gravitational forces.

There are three types of galaxies: elliptical, spiral and irregular shaped. All the galaxies have different shapes of centers. Some may have elongated centers, some can shape like bars.

The galaxies do not change their shape from time to time. Minor changes might be seen but change is shape does not happen.

Hence, the correct statement is both are held together by gravitational forces.