Which are reasons why so many people live on the ring of fire

If we represent the solar system on a scale that allows us to walk from the sun to pluto in a few minutes, then a) the planets are microscopic and the stars are millions of miles away. b) the planets are the size of basketballs and the nearest stars are a few miles away. c) the planets are marble size or smaller and the nearest stars are thousands of miles away.

Solve for r in the formula v = ir, when i = 5 and v = 15.

From the standpoint of geography, a is an internal rendering of an individual's known world