Select the correct answer. In a baseball game, a batter has hit the ball and is running at a speed of 30 feet per second. If the baseball diamond is a square with 90–foot sides, at what rate is the player's distance from home plate changing when he is 70 feet from third base?

A.
5.252 ft./s
B.
18.418 ft./s
C.
23.681 ft./s
D.
48.865 ft./s