Let P={10,20,30} and Q={5,10,15,20}. Which one of the following functions is one – one and not onto?

Options :

1. f={(10,5),(10,10),(10,15),(10,20)}

2. f={(10,5),(20,10),(30,15)}

3. f={(20,5),(20,10),(30,10)}

4. f={(10,5),(10,10),(20,15),(30,20)}