When hot and cold air meet, the hot air rises to the top. Which process causes the hot air to rise? A. conduction B. convection C. induction D. radiation Im not really sure what the answer is.

The description that you provided is literally the description of B. Convection and can be see in any dictionary. Radioactivity is when compounds emit radioactive rays, induction is the process of giving magnetic properties by introducing electricity, and conduction is the ability to transfer electrons and heat through a material.