Let $f ( x ) = \sin x + \cos x$

Multiple Choice

Let $f ( x ) = \sin x + \cos x$ on $[ 0,2 \pi ]$ Then the set of all in c guaranteed by Rolle's Theorem is

A) $\left\{ \frac { 3 \pi } { 4 } \right\}$
B) $\left\{ \frac { 7 \pi } { 4 } \right\}$
C) $\left\{ \frac { \pi } { 4 } , \frac { 5 \pi } { 4 } \right\}$
D) $\left\{ \frac { \pi } { 4 } , \frac { 7 \pi } { 4 } \right\}$
E) $\left\{ \frac { \pi } { 4 } , \frac { 3 \pi } { 4 } \right\}$