Provide an Appropriate Response $f ( x ) = a ^ { x }$

Multiple Choice

Provide an appropriate response.
-Give an equation of the form $f ( x ) = a ^ { x }$ to define the exponential function whose graph contains the point $\left( 2 , \frac { 1 } { 49 } \right)$ . Assume that $a > 0$ .

A) $f ( x ) = 2 ^ { x }$
B) $f ( x ) = \left( \frac { 1 } { 7 } \right) ^ { x }$
C) $f ( x ) = 7^ x$
D) $f ( x ) = \left( \frac { 1 } { 2 } \right) ^ { x }$