The Surface Integral $\int \int$ S $x d S$ Where S Is $x + y + z = 1$

Multiple Choice

The surface integral $\int \int$ S $x d S$ where S is $x + y + z = 1$ in the first octant, is

A) $\frac { \sqrt { 3 } } { 20 }$
B) $- \frac { \sqrt { 3 } } { 21 }$
C) $\frac { \sqrt { 3 } } { 21 }$
D) $\frac { \sqrt { 3 } } { 6 }$
E) $- \frac { \sqrt { 3 } } { 24 }$