A fast-food restaurant operates both a drive-through facility and a walk-in facility. On a randomly selected day, let X and Y, respectively, be the proportions of the time that the drive-through and walk-in facilities are in use, and suppose that the joint density function of these random variables is as shown below. Complete parts (a) through (c). f(x.y) = 3(2x +y), 0sxs1, 0sys1 elsewhere (a) Find the marginal density of X. Select the correct choice below and fill in the answer box to complete your choice. O A. h(y) = for 0sys1 B. g(x)= for 0sxs1 %3D