Answer:
Step-by-step explanation:
There is only one answer. It is the very definition of what a function is.
The answer is A. That is exactly how a function is defined.
You can have minus numbers and still have a function. B is incorrect.
A function should have different x values. If the sample doesn't have different x values but different y values, you don't have a function C is wrong.
D is wrong. You can have a function if all the y values are different. The x values normally should be as well.
