Given a scientific question, generate a correct answer to it.

Input: Consider Input: What type of pollution comes from sewage, storm drains, septic tanks, boats, and runoff from yards?

Output: municipal

Input: Consider Input: When sparks from a steel grinder react with oxygen, what do they form?

Output: iron oxide

Input: Consider Input: Through which organ do hookworm larvae enter the human body?
Output: through the skin