Which relation is a function?
A. {(1,2), (1,5), (1,-1), (1,4)}
B. {(8,-1), (2,-1), (3,8), (2,5}
C. {(-3,4), (-2,5), (0,9), (0,12)}
D. {(7,12), (1,-5), (3,-10), (2,-5)}
By definition, If in a relation the each input value (value of x) has one and only one output value (value of y), then the relation is called "Function".
The option A is not a function because input value (x=1) has more than one input value.
The option B is not a function because input value (x=2) has more than one input value.
The option C is not a function because input value (x=0) has more than one input value.
The option D is a function because each input value (value of x) has one and only one output value.
