Determine which consecutive integers do not have a real zero of f(x) = x^3 + 5x^2 - x - 6 between them.
A(-6, -5)
B(-5, -4)
C(-2, -1)
D(1, 2)
A(-6, -5)
B(-5, -4)
C(-2, -1)
D(1, 2)