Write an Equation for the Graph Given $2 ^ { - x } - 1$

Multiple Choice

Write an equation for the graph given. The graph represents an exponential function f with base 2 or 3, translated and/or
reflected.
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A) $2 ^ { - x } - 1$
B) $2 ^ { x } - 1$
C) $- 2 ^ { x } - 1$
D) $2 ^ { - x } + 1$