Let $G=\frac{R}{\{0\}}$ and $H=\{-1,1\}$ be groups under the multiplication. Then, the map $\phi: G \rightarrow H$ defined by $\phi(x)=\frac{x}{|x|}$ is
- Not a homomorphism
- A one-one homomorphism, which is not onto
- An onto homomorphism, which is not one to one
- An homomorphism