Which of the Following Best Describes a "Rollover"clause in an Elevator

Which of the following best describes a "rollover"clause in an elevator maintenance contract?

A) If the customer does not provide written notice of cancellation early enough before the end of the contract term, the contract will "rollover" into another term.
B) If all of the service outlined in the contract is not used up during the month, the remaining balance of the service is "rolled over" into the next month.
C) If all of the service in the total term of the contract is not used up during that term, the customer continues to receive service until it is all used up.
D) None of the above