Which of the relations given by the following sets of ordered pairs is a function?
Select one:
a. {(2,4),(2,6),(2,8),(2,10),(2,12)(2,4),(2,6),(2,8),(2,10),(2,12)}
b. {(−5,−4),(−4,−3),(−3,−2),(−4,−5),(−2,−1)(−5,−4),(−4,−3),(−3,−2),(−4,−5),(−2,−1)}
c. {(0,3),(−6,8),(−3,5),(0,−3),(7,11)(0,3),(−6,8),(−3,5),(0,−3),(7,11)}
d. {(8,1),(−4,1),(3,5),(0,4),(−1,2)(8,1),(−4,1),(3,5),(0,4),(−1,2)}