The Derivative $\frac { d } { d x } \left[ \int _ { 0 } ^ { \sin x } \sqrt { 1 - t ^ { 2 } } d t \right]$

Multiple Choice

The derivative $\frac { d } { d x } \left[ \int _ { 0 } ^ { \sin x } \sqrt { 1 - t ^ { 2 } } d t \right]$ is

A) cos x
B) cos² x
C) sec x
D) sec² x
E) csc² x