A mass located in the cytoplasm of a cell, separated from the cytoplasm by a nuclear

membrane; considered the control center of the cell.

A. mitochondria

B. nucleolus

C. pinocytic vesicle

D. nucleus

D

Explanation:

Nucleus contains all the genetic material that codes for different proteins that control the cell's actions. It's surrounded by a nuclear membrane.

However,

Mitochondria is used for energy production and isn't surrounded by a nuclear membrane. It's in fact surrounded by 2 membranes.

Pinocytic vesicles usually contain endocytosed material from outside that has nothing to do with the cell's control.

Nucleolus is inside the nucleus and is used to make rRNA needed for ribosomes production. A nucleolus is not surrounded by any membrane.