Determine which of the following mappings are linear mappings.

Question

A. The mapping L defined by L(x_1, x_2 ) = (4x_1- 2x_2, 3 |x_2|).
B. The mapping L defined by L(x_1, x_2 ) = (2x_1-3x_2, x_1+4, 5x_2).
C. The mapping L defined by L(x_1, x_2, x_3 ) =(x_1, 0 , x_3).
D. The mapping L defined by L(x_1, x_2, x_3 ) =(1, x_2, x_3).
E. The mapping L defined by L(x_1, x_2, x_3 ) =(x_1, x_2, -x_3).