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

### Question:
If a child scrapes his foot on a piece of rusty metal, it is important to get medical treatment because the

### Choices:
A. metal is corrosive to the skin.
B. foot carries large amounts of bacteria.
C. foot is the most sensitive part of the body.
D. metal may be contaminated and cause infection.

### Answer:
