JEE MATHEMATICS MCQ: FUNCTIONS

Let $\mathrm{A}$ and $\mathrm{B}$ be non-empty sets. Let $f: \mathrm{A} \rightarrow \mathrm{B}$ and $g: \mathrm{B} \rightarrow \mathrm{A}$ be two functions such that $f(g(x))=x, \forall x \in \mathbf{B}$. Which of the following statements are true (T) or false (F) ?
(i) The function $f$ is one-one function
(ii) The function $f$ is onto
(iii) The function $g$ is one-one
(iv) The function $g$ is onto