Which relation is a function?
{(5, 1), (4, 9), (6, 10)}
{(0, 3), (0, 9), (12, 4)}
{(5, 5), (5, 9), (5, 15)}
{2, 10), (6, 10), (2, 3)}
the third one?
The First one, because you can't have the first number in the set repeat.
In the second choice 0 repeats twice as the first number in the set (the input)
In the third choice 5 repeats twice as the first number in the set
In the fourth choice 2 repeats twice as the first number in the set.
So the correct answer should be A!
Hope this helps!!