Let $z = 2 x ^ { 2 } - 7 y$

Multiple Choice

Let $z = 2 x ^ { 2 } - 7 y$ , where x = sin t and y = cos t. When t =?, $\frac { d z } { d t }$ is

A) $\pi$
B) 0
C) $\frac { \pi } { 3 }$
D) $\frac { \pi } { 4 }$
E) $\frac { \pi } { 5 }$