Find all relative extrema of the function f(x)=-xsquare root of 3+2cosx?

I don't even know how to start this problem off. I need steps, please. My choices are A- relative maxima at x=pi/4+2pin, rel. min. at x=5pi/4+2pin, for any integer n B-relative maxima at x=pi/3+2pin, rel. min. at x=4pi/3+2pin, for any integer n C-relative maxima at x=4pi/3+2pin, rel. min. at x=5pi/3+2pin, for any integer n D- none of these