Here's a problem to solve: If a child scrapes his foot on a piece of rusty metal, it is important to get medical treatment because the

Among the 4 following options, which is the correct answer?

- 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.
 