Tag one shark and monitor its eating habits for one day. Tag one shark and monitor its eating habits for one year. Tag several sharks and monitor their eating habits for one day. Tag several sharks and monitor their eating habits for one year.
I gave my students this multiple choice question: What is the best way for a marine scientist to determine the eating habits of sharks?

Only one answer is correct among these 4 choices:
- Tag one shark and monitor its eating habits for one day.
- Tag one shark and monitor its eating habits for one year.
- Tag several sharks and monitor their eating habits for one day.
- Tag several sharks and monitor their eating habits for one year.

Could you tell me which one is correct?

Tag several sharks and monitor their eating habits for one year.