Which of the following statements best gives the reasons that a data usage bill for a smart phone is an essential (variable) expense?

A data usage bill is an obligation because the customer must pay for the service used, but the amount can vary with how much data is consumed or the plan chosen. That matches choice a: “It is an obligation to pay, but the spender has some control over its amount.” A bill that is expected to be the same every month would be a fixed expense, not a variable one.

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