Two Objects of Differing Masses $\left( m _ { a } , m _ { b } \right)$

Two objects of differing masses $\left( m _ { a } , m _ { b } \right)$ are placed at the top of two frictionless inclines having the same height. Mass $m _ { a }$ is on an incline that makes an angle of $15 ^ { \circ }$ with the horizontal; mass $m _ { b }$ is on an incline that makes an angle of $75 ^ { \circ }$ with the horizontal. The masses are released at the same time. The mass that reaches the bottom first is

A) $m _ { a }$
B) $m _ { b }$
C) Both masses reach the bottom at the same time.
D) This cannot be determined unless both the masses ( $m _ { a } , m _ { b }$ ) are known.