Consider the Following Two Functions

Multiple Choice

Consider the following two functions:
g(x, y) =4x - 3y + 21
H(x, y) = 13xy
Which of the following is true regarding the linearity of the functions?

A) neither of the functions is linear
B) both functions are linear
C) g(x, y) is linear, but h(x, y) is not linear
D) h(x, y) is linear, but g(x, y) is not linear
E) h(x, y) is not linear, and g(x, y) is only linear when y ? 0