Which relation is a function?

number graph ranging from negative four to four on the x and y axes. points are drawn on the graph at begin ordered pair negative three comma negative one end ordered pair and begin ordered pair negative two comma three end ordered pair and begin ordered pair zero comma negative three end ordered pair and begin ordered pair one comma negative two end ordered pair and begin ordered pair two comma two end ordered pair and begin ordered pair three comma zero end ordered pair

number graph ranging from negative four to four on the x and y axes. points are drawn on the graph at begin ordered pair negative four comma three end ordered pair and begin ordered pair negative two comma one end ordered pair and begin ordered pair negative one comma three end ordered pair and begin ordered pair negative one comma negative one end ordered pair and begin ordered pair one comma one end ordered pair and begin ordered pair two comma negative one end ordered pair

number graph ranging from negative four to four on the x and y axes. points are drawn on the graph at begin ordered pair negative two comma one end ordered pair and begin ordered pair negative two comma negative two end ordered pair and begin ordered pair negative one comma three end ordered pair and begin ordered pair zero comma one end ordered pair and begin ordered pair two comma zero end ordered pair and begin ordered pair two comma negative two end ordered pair

number graph ranging from negative four to four on the x and y axes. points are drawn on the graph at begin ordered pair negative two comma one end ordered pair and begin ordered pair negative one comma three end ordered pair and begin ordered pair zero comma two end ordered pair and begin ordered pair zero comma negative one end ordered pair and begin ordered pair one comma three end ordered pair and begin ordered pair two comma one end ordered pair