For real $$x$$, let $$f(x) = x^3 + 5x + 1$$, then

A

$$f$$ is one-one but not onto $$R$$

B

$$f$$ is onto $$R$$ but not one-one

C

$$f$$ is one-one and onto $$R$$

D

$$f$$ is neither one-one nor onto $$R$$