A single cell includes many specialized parts and organelles to carry out various processes. For example, the endoplasmic reticulum is a complicated network of folded membranes with a large amount of surface area on which chemical reactions are carried out.
Which of the following statements best explains how the specialized parts of cells came to have their current form?
A.
Cellular differentiation in multicellular organisms created many different kinds of cells. The cells that were most helpful to the organism survived and reproduced.
B.
Ancient single-celled organisms competed for food, energy, and raw materials. Natural selection favored cells that could compete effectively.
C.
Cells formed colonies that worked together for food, energy, and raw materials. Single-celled organisms could not compete with the colonies and died out.
D.
Cell organelles have remained unchanged since the first cells came into existence. Each organelle is formed exactly as it must be for the cell to survive.