Answer:
B
Explanation:
We are given that four graphs
We have to find that which graph does not represent a function.
Function: It is defined as mapping between x and y .
When we substitute x in the given function then we get corresponding value of x is y.
It is written as

First graph is the graph of parabola along y- axis .The equation of parabola along y- axis is given by

By definition of function, it represents function.
B.The given graph is a vertical line
Equation of vertical line,x=a
We have x=3
There are no value of y.
Because the value of y on x - axis is 0.
Hence, the graph does not represent a function by the definition of function.
C.The given graph is an equation of a line.
Equation of line represent a function because we get the value of y corresponding of x.
D.The given graph represent the graph of logarithm function.
It is always represent a function by the definition of function.
Hence, option B is true.