Star Clusters Provide a Way to Test Stellar Evolution Theory

Star clusters provide a way to test stellar evolution theory because

A) all the stars in a cluster are the same age and the same type.
B) all the stars in a cluster are different ages and come in many different types.
C) all the stars in a cluster are the same age and come in many different types.
D) all the stars in a cluster are different ages and the same type.