Why do you think a runner will most likely develop bigger leg bones than a swimmer? how does this happen?

The genetics and the bone structure determines the shape of the leg. However, running can change your bones, because bones experience huge forces during movement. Long-distance running builds leaner muscles, while sprinting adds bulk. Bones from swimmer are not much different from the bones of people who don't exercise.High impacts (hitting the floor from a jump, or striking a tennis ball) are needed to produce big enough muscle and impact forces to make our bones change. This is the reason why running changes our bones, and swimming does not.

D, capsid protien, its the protein shell of a virus.