Final answer:
A function is a relation between two sets of values where each input value is associated with exactly one output value. The set (2, 1), (3, 1), (4, 3), (5, 3) represents a function.
Step-by-step explanation:
A function is a relation between two sets of values, where each input value (x) is associated with exactly one output value (y).
Looking at the given sets of ordered pairs:
A. (1, 8), (8, 1), (1, 5), (5, 1) - In this set, the input value '1' is associated with multiple output values '8' and '5', violating the definition of a function.
B. (2, 1), (3, 1), (4, 3), (5, 3) - In this set, each input value is associated with only one output value, satisfying the definition of a function.
C. (5, 1), (3, 8), (3, 7), (7, 1) - In this set, the input value '3' is associated with multiple output values '8' and '7', violating the definition of a function.
D. (5, 1), (5, 6), (1, 3), (9, 7) - In this set, the input value '5' is associated with multiple output values '1' and '6', violating the definition of a function.
Therefore, the set of ordered pairs that represents a function is B. (2, 1), (3, 1), (4, 3), (5, 3).