Consider the following three functions: g(x, y) = 4x - 9y? h(x, y, z) = 13x + y + 32 - 6 ily, z) = Z - y Which of the following is true regarding the linearity of the functions? Select one: A. h is linear, but g and i are not linear. B. i is linear, but g and h are not linear. C. h and i are linear, but g is not linear. O D. g is linear, but h and i are not linear. O E. All three functions are linear