Concept:The mapping shows a constant decrease in y as x increases by 1.So the rule is a linear equation of the form y=mx+c.Explanation:For each step in x, the y-values are: 4,2,0,−2,−4.The difference between consecutive y-values is −2, so the slope is m=−2.Use the first pair (x=1,y=4) in y=mx+c.Substitute m=−2, x=1, and y=4: 4=−2(1)+c.Simplify: 4=−2+c, so c=4+2=6.Hence the rule is y=−2x+6.Check: for x=2, y=−2(2)+6=2; for x=3, y=0.This matches the given mapping exactly.Answer:y=−2x+6 (Option D).