Which graph represents a function? i think a.

graph B ( the lower one )

for a function to be defined there can only be one value of y for each value of x

graph A has more than 1 value of y for given values of x

for example ( - 1, 4 ) and  ( - 1, - 4 ) thus is not a function

graph B only has 1 value of y for a given value of x thus is a function

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