Which set of ordered pairs represents a function? {(−1,−3),(0,−7),(3,3),(3,−4)} {(7,9),(−5,7),(−5,8),(4,−4)} {(−6,−1),(−8,4),(−5,4),(3,−9)} {(−1,0),(−1,−4),(8,−3),(−4,−6)}