Which of the following is a control activity in relation to cut-off?

a. The accountant reviews whether invoices have been received and processed for all building repairs purchase orders.

b. When rental income is received, the accountant checks to ensure that the rental agreement with the tenant has not lapsed.

c. At the end of each month, the accountant reviews whether income has been received for all current rental agreements.

d. The accountant reviews building repairs invoices around year-end to see which period they are recorded in.