Answer: According to the definition, the function is a relationship between two sets of numbers that matches numbers from one set to another:
Diagram for the Illustration:
Do note! That the single input can not have two outputs.
Therefore the answer is:
![\begin{gathered} \text{ Relation \lparen1\rparen}\rightarrow\text{ Not a Function} \\ \\ \text{Relat}\imaginaryI\text{on}\operatorname{\lparen}\text{2}\operatorname{\rparen}\operatorname{\rightarrow}\text{Funct}\imaginaryI\text{on} \\ \\ \text{Relat}\imaginaryI\text{on}\operatorname{\lparen}\text{2}\operatorname{\rparen}\operatorname{\rightarrow}\text{ Not a Funct}\imaginaryI\text{on} \\ \\ \text{Relat}\imaginaryI\text{on}\operatorname{\lparen}\text{2}\operatorname{\rparen}\operatorname{\rightarrow}\text{ Not a Funct}\imaginaryI\text{on} \end{gathered}]()
![\begin{gathered} \text{ Relation \lparen1\rparen}\rightarrow\text{ Not a Function} \\ \\ \text{Relat}\imaginaryI\text{on}\operatorname{\lparen}\text{2}\operatorname{\rparen}\operatorname{\rightarrow}\text{Funct}\imaginaryI\text{on} \\ \\ \text{Relat}\imaginaryI\text{on3}\operatorname{\rparen}\operatorname{\rightarrow}\text{ Funct}\imaginaryI\text{on} \\ \\ \text{Relat}\imaginaryI\text{on\lparen4}\operatorname{\rparen}\operatorname{\rightarrow}\text{ Not a Funct}\imaginaryI\text{on} \end{gathered}]()
Or the relation(2) and (3) are functions, and the rest are not functions.