Find the Slope of the Curve at the Indicated Point $v$

Find the slope of the curve at the indicated point.
-For a motorcycle traveling at speed $v$ (in $m p h$ ) when the brakes are applied, the distance $d$ (in feet) required to stop the motorcycle may be approximated by the formula $\mathrm { d } = 0.05 \mathrm { v } ^ { 2 } + \mathrm { v }$ . Find the instantaneous rate of change of distance with respect to velocity when the speed is $46 \mathrm { mph }$ .

A) 5.6 mph
B) 47 mph
C) 11.2 mph
D) 4.6 mph