If `lim_(xrarr0)(x^(-3)sin3x+a x^(-2)+b)` exists and is equal to 0, then (a) `a=-3` and `b=9/2` (b) `a=3` and `b=9/2` (c) `a=-3` and `b=-9/2` (d) `a=3` and `b=-9/2`