A 200-N Crate Rests on a Ramp; the Maximum Angle $\degree$

Multiple Choice

A 200-N crate rests on a ramp; the maximum angle just before it slips is 21 $\degree$ with the horizontal. What is the coefficient of static friction between crate and ramp surfaces?

A) 0.11
B) 0.21
C) 0.38
D) 0.47