Answer:
B. it is a function because every Celsius tepmerature is associated with only one Fahrenheit temperature.
Explanation:
We are given that the temperature in degrees Celsius C can be converted to degrees Fahrenheit F
We know that the formula

If we are substituting

Then , we get

For every Celsius temperature we get only one value of Fahrenheit .
Function: function is a mapping between two sets .Each member of set is mapped with one value of set B.
Given function is one-one because for every value of Celsius we get a unique value of Fahrenheit
Hence, it is a function because every Celsius tepmerature is associated with only one Fahrenheit temperature.
Therefore, option B is true.