A ball is dropped from a height of 20 feet above the ground. The velocity v(s) of the ball after it has travelled a distance of s feet is modeled by the function v(s) = 60s. What is the domain of the function v(s) in terms of the context?
(A) All positive integers
(B) All positive real numbers
(C) All integer greater than or equal to 0 and less than or equal to 20
(D) All real numbers greater than or equal to 0 and less than or equal to 20