Answer:

Step-by-step explanation:
Let's define each answer choice.
A. Density
- The amount of mass in a certain space
B. Buoyancy
- The tendency of an object to float on a fluid/water
C. Magnetism
- The ability of objects to product attracting or repulsing fields
D. Solubility
The definition that matches "the ability for something to float on water" is buoyancy. Therefore, the correct answer is B. Buoyancy