Answer:
D. Both a relation & a function.
Step-by-step explanation:
A relation is a set of one or more ordered pairs. A function is a relation in which each input has exactly one output. A set of ordered pairs represents a function if, for every value of x, there is only one value of y. In the given situation, the x-coordinate is the number of weeks since she starts recording and the y-coordinate is the number of books read per week. It can be seen from the given set that each x-value corresponds with exactly one y-value. Therefore, the set of ordered pairs is best described as both a relation and a function.
