The Graph of an Exponential Function Is Given $f ( x ) = 2 ^ { - x }$

Multiple Choice

The graph of an exponential function is given. Select the function for the graph from the functions listed.
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A) $f ( x ) = 2 ^ { - x }$
B) $f ( x ) = 2 ^ { x }$
C) $f ( x ) = - 2 ^ { x }$
D) $f ( x ) = - 2 ^ { - x }$