f is a function with the following Fourier coefficients

${\rm a}_0 = 0$
${\rm a}_1 =0$	${\rm b}_1 = -1$
${\rm a}_2 =-{\frac{1}{3}}$	${\rm b}_2 = {\frac{1}{3}}$
${\rm a}_3 =-1$	${\rm b}_3 = -{\frac{1}{3}}$

Which of the following is the graph of f? ? A B C D