Which equation could be used to solve for measure of side q in (Triangle) QRS shown below, given s=15*, S=45*, and Q = 105*?

Answer choices:
a) 15/sin 105* = q/sin45*
b) sin 105*/q = sin 30*/15
c) sin 105*/15 = sin 30*/q
d) q/sn 105* = 15/sin 45*