The answer would be letter A. globular cluster. This group of very old stars that are clustered together in a spherical in shape and can contain from 10,000 to several million is called a globular cluster. In our galaxy, there are 150 globular clusters.
Traits that are passed down on an X or a Y chromosome are sex-linked traits. Most of the time males are affected by sex-linked traits because males only have one X and a Y. The Y is the chromosome that makes a man, a man.