Which of the following functions are solutions of the differential equation y'' + y = 3 sin(x)? (Select all that apply.)
a. y = 3 sin(x)
b. y = 3/2x sin(x)
c. y = 3x sin(x)-4x cos(x)
d. y = 3 cos(x) e. y = -3/2x cos(x)