Let $$f: \mathbb{R} \to \mathbb{R}$$ be defined as $$f(x) = \dfrac{2x^2 - 3x + 2}{3x^2 + x + 3}$$. Then $$f$$ is :

A

both one-one and onto

B

one-one but not onto

C

onto but not one-one

D

neither one-one nor onto