What is the dimensional formula of $$ab^{-1}$$ in the equation $$\left(P + \frac{a}{V^2}\right)(V - b) = RT$$, where letters have their usual meaning.

A

$$[M^{-1} L^5 T^3]$$

B

$$[M^6 L^7 T^4]$$

C

$$[ML^2 T^{-2}]$$

D

$$[M^0 L^3 T^{-2}]$$