Here's a problem to solve: Pumice is formed when magma blows out of a volcano and cools quickly. Pumice is the only rock that will float because pumice

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

- A: is a hard mineral.
 
- B: was once a liquid.
 
- C: is an igneous rock.
 
- D: contains air pockets.
 