Provide an Appropriate Response $\frac { \mathrm { dv } } { \mathrm { dt } } = 0$

Provide an appropriate response.
-A catamaran is running along a course with the wind providing a constant force of 30 lb. The only other force acting on the boat is resistance as the boat moves through the water. The resisting force is numerically equal to Two times the boat's speed, and the initial velocity is 1 ft/sec. What is the maximum velocity in feet per second Of the boat under this wind?

A) The maximum velocity occurs when $\frac { \mathrm { dv } } { \mathrm { dt } } = 0$ or $\mathrm { v } = 12 \mathrm { ft } / \mathrm { sec }$
B) The maximum velocity occurs when $\frac { \mathrm { dv } } { \mathrm { dt } } = 0$ or $\mathrm { v } = 15 \mathrm { ft } / \mathrm { sec }$
C) The maximum velocity occurs when $\frac { \mathrm { dv } } { \mathrm { dt } } = 15$ or $\mathrm { v } = 0 \mathrm { ft } / \mathrm { sec }$
D) The maximum velocity occurs when $\frac { \mathrm { dv } } { \mathrm { dt } } = 12$ or $\mathrm { v } = 0 \mathrm { ft } / \mathrm { sec }$