If $$ax^4 + bx^3 + 2x^2 + 4$$ is exactly divisible by $$x^2 - x - 2$$, then $$(a, b) =$$ 

A

$$\left(\frac{1}{2}, -\frac{3}{2}\right)$$

B

$$\left(\frac{3}{2}, \frac{5}{2}\right)$$

C

$$\left(\frac{5}{2}, \frac{7}{2}\right)$$

D

$$\left(-\frac{5}{2}, \frac{7}{2}\right)$$