In the Previous Two Problems, If the Mass Is Set $x ( t )$

In the previous two problems, if the mass is set into motion in a medium that imparts a damping force numerically equal to 16 times the velocity, the correct differential equation for the position, $x ( t )$ , of the mass at a function of time, $t$ , is

A) $\frac { d ^ { 2 } x } { d t ^ { 2 } } + 4 \frac { d x } { d t } + x / 4 = 0$
B) $\frac { d ^ { 2 } x } { d t ^ { 2 } } + 4 \frac { d x } { d t } + 2 x = 0$
C) $\frac { d ^ { 2 } x } { d t ^ { 2 } } + 4 \frac { d x } { d t } + 4 x = 0$
D) $\frac { d ^ { 2 } x } { d t ^ { 2 } } + 4 \frac { d x } { d t } + 8 x = 0$
E) $\frac { d ^ { 2 } x } { d t ^ { 2 } } + 4 \frac { d x } { d t } + 32 x = 0$