Question

Why is a cork able to float on water?
A. small in size
B. a solid
C. less dense than water
D. equal in density to water

Answer 1

C. Less dense than water

Answer 2

I believe the answer would be C, less dense than water. 
The reason to why it floats because things like wood, cork, and ice tend to be less dense than water, hence they float. A rock, for example, is denser, so they sink. 

I hope this answers your question, good luck on your assignment.