Answer:
B. C. and D.
Step-by-step explanation:
You just have to make sure that every input has ONE output. Or every x-value has a single y-value.
You can have (1,2) (4,8) and (7,12) but you can't have (1,2) (1,4) (2,4)
If you need me to go over it again, let me know! Hopefully this helps, and have a great day!
