Solve the Problem $v$ (In Mph) When the Brakes Are Applied, the Distance D

Multiple Choice

Solve the problem.
-For a motorcycle traveling at speed $v$ (in mph) when the brakes are applied, the distance d (in feet) required to stop the motorcycle may be approximated by the formula $d = 0.05 v ^ { 2 } + v$ . Find the instantaneous rate of change of distance with respect to velocity when the speed is $40 \mathrm { mph }$ .

A) 41 mph
B) 5 mph
C) 10 mph
D) 4 mph