A cook takes a hot iron frying pan off the stove to cool. What happens as the iron pan cools

1. The mass of the iron atoms increases, so the pan gets a tiny bit heavier.
2. The mass of the iron atoms does not change, so the pan remains the same.
3. The distance between the iron atoms decreases, so the pan gets a tiny bit smaller.
4. The distance between the iron atoms does not change, so the pan remains the same.

3. is true.

2. would also be true if it said "...so the mass of the pan remains the same".

1. and 4. are certainly false.