(4) (HAND IN) Use the substitution (z = ey) to turn the equation below into a linear equation in (z): (dy/dx = sin(x + 1)e-y + x/2).
a) (zey = sin(x + 1) + x/2)
b) (zsin(x + 1) = ey + x/2)
c) (z + ey = sin(x + 1) + x/2)
d) (zsin(x + 1) = e-y + x/2)