Answer:
A) It is an obligation to pay, but the spender has some control over its amount.
Explanation:
An essential expense is an important expense required for living. These expenses can be fixed or variable. Fixed expense remains same but variable expense changes.
Here, in the given scenario, the data usage bill is variable as it depends completely on the usage. If the user is using more data, the bill will be more. If the data usage is lower, the bill will be less.
Therefore, option A is the right answer.