B. Nucleus
Explanation:
The nucleus would be classified as the control center for the cell. Only eukaryotic cells will contain a nucleus and they are surrounded by cytoplasm.
In the cell, a nucleus is very important to have. One of the most important jobs of the nucleus is the holding of genetic material. Genetic material can be either RNA or DNA, but in this case it is DNA. The nucleus holds DNA, which is obviously very important as it stores genes and heredity information.
The nucleus controls all of the important functions of a cell.
