If R Is the Region Bounded by Y = X $\iint$

Multiple Choice

If R is the region bounded by y = x, x = ? and the x-axis, then $\iint$ R $\cos ( x + y ) d A$ is

A) $- 3$
B) $- 2$
C) $- 1$
D) $- \frac { 1 } { 2 }$
E) $- \frac { 1 } { 4 }$