Let $f: R \to R$, be defined as $f(x) = x^4$. Choose the correct answer.

Question

$$\begin{array}{1 1}(A)\;f\;is\;one-one\;onto. & (B)\;f\;is\;many-one\;onto.\\(C) \;f\;is\;one-one\;but\;not\;onto. & (D)\;f\;is\;neither\;one-one\;nor\; onto.\end{array}$$