Answer:
1 and 4- Yes
2, 3, 5, 6 - No
Explanation:
1.
Yes. Each input has corresponding output
2.
No. Repeat inputs with different outputs
3.
No. Doesn't pass vertical line test. One input with different outputs.
4.
Yes. Unique inputs and outputs.
5.
No. One input with two outputs
6.
No. One input with two outputs.