B
Below is a question with multiple-choice answers. Choose the correct option based on your reasoning.

### Question:
An elephant is a multicellular organism that weighs about 200 pounds at birth and can grow to weigh as much as 15,000 pounds. What increases as the elephant grows into an adult?

### Choices:
A. the size of each body cell
B. the number of cells in its body
C. the amount of energy in its cells
D. the collection of water in each cell

### Answer:
