Solve the Problem $\mathrm { F }$ Of a Car Traveling Up or Down a Hill Is

Solve the problem.
-The grade resistance $\mathrm { F }$ of a car traveling up or down a hill is modeled by the equation $\mathrm { F } = \mathrm { W } \sin \theta$ , where $W$ is the weight of the car and $\theta$ is the angle of the hill's grade $\theta > 0$ for uphill travel, $\theta < 0$ for downhill travel) . A $1900 - \mathrm { lb }$ car has just rolled off a sheer vertical cliff $\left( \theta = - 90 ^ { \circ } \right)$ . What is the car's grade resistance?

A) $1900 \mathrm { lb }$
B) $- 1900 \mathrm { lb }$
C) $0 \mathrm { lb }$
D) undefined