B.) A giant elliptical galaxy
At the center of a large cluster, you'll usually find large and massive galaxies.
In the Milky Way galactic halo, orbiting the galactic center in a long elliptical orbit around the galactic center
Yes, However all galaxies are the same (simplified): A bunch of solar systems turning around a massive black hole. The forms are often very different, you have elliptical (elliptic formed) galaxies, spiral ("arms" from the center turning around it, circular) galaxies and irregular (irregular ;P) galaxies.
They are formed at the SHlT center
Both have a huge black hole at their center.
A giant elliptical galaxy at the center of a dense cluster
Elliptical galaxies are made of old stars and not very much gas or dust.
A giant elliptical galaxy at the center of a dense cluster
Galaxies that appear to have a bulge in the middle and arms that spherical outward, like pinwheels, are spherical. Elliptical galaxies look like round or flattened balls. Galaxies that do not have regular shapes are known as irregular galaxies.
The center is crowded with stars, and the number of stars decreases farther out.
The nearest cluster of galaxies is the "Virgo Cluster" discovered by Charles Messier in 1784. The Virgo cluster lies at/near the center of the Supercluster we belong to - also called the "Virgo Supercluster". Our "Local Group" (comprising of The Milky way, Andromeda, and another 25-30 smaller galaxies) is part of the Virgo Cluster. The center of the Virgo cluster is at a distance of about 18 Mpc (Mega parsecs) approx 60 Million lightyears from us [which translates to a 'redshift' of only z=0.004]. Ain't the universe huge? Note: There are quite a few 'groups of galaxies' between us and the center of Virgo Cluster.
All galaxies are massive clusters of stars scattered across the universe. Many galaxies take the same form, for instance, spiral and elliptical galaxies. Some galaxies also have a black hole in their center.