Which set of ordered pairs in the from of (x,y) does not represent a function of x?

Question

{(1,1.5), (2,1.5), (3,1.5) (4,1.5)}(my guess)
{(0,1.5), (3,2.5), (1,3.3), (1, 4.5)}
{(1,1.5), (-1,1.5), (2,2.5), (-2,2.5)}
{(1,1.5), (-1,-1.5),(2,2.5),(-2,-2.5)}

Answer 1

If two or more points lie on the same vertical line, then you DON'T have a function, so ... look for a set of points that have 2 or more like x's

Your "guess" of A) is incorrect

(In cases like this "guessing" is not a mathematical procedure)

Answer 2

I did t know the answer so I guessed using the knowledge I had. Could you tell me which is correct?

Answer 3

Would it be B then because it has two x values that are same?

Answer 4

Yes, it was the only one that fits the definition, so need to guess.