Find k such that the function is a probability density function over the given interval. Then write the probability density function. f(x)=k(3-x): [0, 3] ok A. 3; f(x)=3(3-x) B. 9:1(x)=9(3-X) 1 Oc.(x)=(3-X) OD. f(x)=(3-X)