STEP 1: Recall what is a relation

A **relation** is a **relationship** between sets of values. In **math**, the **relation** is between the x-values and y-values of ordered pairs. The set of all x-values is called the domain, and the set of all y-values is called the range.The brackets are used to show that the values form a set.

https://study.com/academy/lesson/relation-in-math-definition-examples.html

STEP 2: Recall what are ordered pairs

A pair of numbers used to locate a point on a coordinate plane is called an ordered pair. An ordered pair is written in the form (x, y) where x is the x-coordinate and y is the y-coordinate.

https://www.splashmath.com/math-vocabulary/algebra/ordered-pair

STEP 3: Recall what is a mapping diagram

A function is a special type of relation in which each element of the domain is paired with exactly one element in the range . A **mapping** shows how the elements are paired. Its like a flow**chart** for a function, showing the input and output values. A **mapping diagram** consists of two parallel columns.

https://www.varsitytutors.com/hotmath/hotmath_help/topics/mapping-diagrams

STEP 4: Recall when a relation is a function

https://www.varsitytutors.com/hotmath/hotmath_help/topics/mapping-diagrams

Choose the correct option

Option 1 is the correct choice since every element of the domain is related to every element of the range with no element in the domain being leftover.

Skills you may want to further recall:

What is a domain and range

https://www.varsitytutors.com/hotmath/hotmath_help/topics/domain-and-range