The figure shows the graph of a trigonometric function.

The function graphed is $f(x) =$ .

Hint: The function may be written as $f(x) = a \sin\left(\frac{2\pi}{P}(x-b)\right)+c$ or $f(x) = a \cos\left(\frac{2\pi}{P}(x-b)\right)+c$ (or both), where $a$, $b$, $c$, and $P$, are integers.