Which of the following represents a function?

Functions cannot have different values of y for the same value of x. Now let us check each case one at a time.
First Case: For the same value of x=-1, y has two different values of 7 and 1, which is not allowed in a function. Therefore, the first case is not a function.
Second Case: For the same value of x=-1, y has two different values of -5 and 1, which is not allowed in a function. Therefore, the second case is not a function.
Third Case: For the same value of x=3, y has two different values of 2 and 4, which is not allowed in a function. Therefore, third case is not a function.
Fourth Case: In this case no value of x is same. So, this is a function.
A relation can be regarded as a function if the x values are unique for every y-value.
The relation (option d) represents a function
(a) The table
The table has the same x-values for y values of 7 and 1.
i.e
[tex]\mathbf{(x,y) = (-1,7),(-1,1)}[/tex]
Hence, the table is not a function
(b) The graph
The graph has the same x-values for y values of -5 and 1.
i.e
[tex]\mathbf{(x,y) = (-1,-5),(-1,1)}[/tex]
Hence, the graph is not a function
(c) The ordered pair
The ordered pair has the same x-values for y values of 2 and 4.
i.e
[tex]\mathbf{(x,y) = (3,2),(3,4)}[/tex]
Hence, the ordered pair is not a function
(d) The relation
For every y-value, there is a corresponding and unique x-value.
Hence, the relation is a function
Read more about functions and relations at:
https://brainly.com/question/6241820