$\text { Find all values of } c \text { such that } f \text { is continuous on } ( - \infty , \infty ) \text {. }$

Multiple Choice

$\text { Find all values of } c \text { such that } f \text { is continuous on } ( - \infty , \infty ) \text {. }$ $$f ( x ) = \left\{ \begin{array} { l l } 4 - x ^ { 2 } , & x \leq c \\x , & x > c\end{array} \right.$$

A) $c = 3$
B) $c = 0$
C) $\frac { - 1 + \sqrt { 17 } } { 2 }$
D) $\frac { 1 + \sqrt { 17 } } { 2 } , \frac { 1 - \sqrt { 17 } } { 2 }$
E) $\frac { - 1 + \sqrt { 17 } } { 2 } , \frac { - 1 - \sqrt { 17 } } { 2 }$