Which of the following best describes the graph below?

a. it us a one-to-one function

b. it us a function but it is not one-to-one

c. it is not a function.

d. it is a many-to-one function.

Option: A is the correct answer.

             A. it is a one-to-one function  

Function--

A graph is one-one when a vertical line is drawn parallel to the y-axis and passing through the domain should intersect the curve exactly once.

i.e. it passes a vertical line test.

One-one function-

A function is said to be one-one if corresponding to each x we get a distinct y-value.

i.e. No two x have the same y-value.

Also it can be seen from the graph when any horizontal line is drawn parallel to the x-axis then the line intersect the curve atmost once.

        i.e. it passes the horizontal line test.

Many-to-one function--

A function is many to one when many x-values are mapped to same y-value.

Clearly from the graph we see that the graph is a one-to-one function.

           ( As it passes the horizontal line test)