Determine the intervals over which f(x) = x* -4x'+ 12 is increasing or decreasing. a.) f(x) is decreasing on ( - co,0) U(0,3). O f(x) is increasing on (3,00). b.) f(x) is decreasing on ( - co, 3). O f(x) is increasing on (3,00). c.) f(x) is decreasing on ( - oo,0), (3,00). O f(x) is increasing on (0,3). d.) f(x) is decreasing on (0,3). O f(x) is increasing on (3, co)