Answer. if you dont know the answer plz dont answer

The answer is C !! hope this helps:)

oops i guess it was A ?? agh i have autism

The answer would be A.  The question asks for how much would be charged if she went over her 300 minutes, so we can assume that the payment regards for only one month.  So the first part of the function should contain for one month:
39.99
If she were to go over her 300 minutes, then she would have to pay $.20 extra per minute.  If x is the number of minutes in total, AND she is talking about a function that would apply if she went OVER 300 minutes, then you should add:
0.20(x-300) 
to the rest of the equation.  The (x-300) is the number of minutes she used AFTER using her original 300 minutes up.  Multiplying.20 per minute by (x-300) will give us the extra money she will have to pay.  At the end, the answer would be 39.99 + 0.20(x-300), or again, A.

Cdoes not have two variables

It is important because sometimes ur dna needs to multiply