a scale and weights a magnet a sieve a battery and wire
I gave my students this multiple choice question: A student is given a mixture of gravel and sand and instructed to separate them. Which tool should the student use to best complete this task?

Only one answer is correct among these 4 choices:
- a scale and weights
- a magnet
- a sieve
- a battery and wire

Could you tell me which one is correct?

a sieve