Given:
Cost of four lines = $125
Cost of each additional line = $15
Jason wants to spend at most $200 per month on cell phone expenses.
To find:
The inequality for the given situation.
Solution:
Let
be the number of additional line.
Cost of one additional line = $15
Cost of
additional line = 
Total cost = Fixed cost + Addition cost
= 
It is given that Jason wants to spend at most $200 per month on cell phone expenses. It means the total cost must be less than or equal to 200.

Therefore, the correct option is C.