Which relation is a function?:)
A. {( 1 , 2) , ( 2 , 3 ) , ( 3 , 4 ) , ( 4 , 5 )}
B. {( 1 , 2 ) , ( 1 , 3 ) , ( 1 , 4 ) , ( 1 , 5 )}
C. {( 1 , 2 ) , ( 2 , 3 ) , ( 3 , 4 ) , ( 2 , 5)}
D. {( 1 , 2 ) , ( 3 , 2 ) , ( 3 , 3 ) , ( 4 , 2 )}