Given:
The relations in the options.
To find:
The relation which is a function.
Solution:
Consider the options are :
(a) {(2, 7), (6, 5), (4, 4), (3, 3), (2, 1)}
(b) {(9, −3), (9, 3), (4, −2), (4, 2), (0, 0)}
(c) {(1, 0), (3, 0), (1, 1), (3, 1) (1, 3)}
(d) {(1, 1), (2, 2), (3, 3), (4, 4), (5, 8)}
A relation is a function if there exist a unique y-value for each x-value.
In option (a), y=7 and y=1 at x=2. So, it is not a function.
In option (b), y=-3 and y=3 at x=9. So, it is not a function.
In option (c), y=0 and y=1 at x=3. So, it is not a function.
In option (d), there are unique y-value for each x-value. So, it is a function.
Therefore, the correct option is (d).