21. Which of the following is a control activity in relation to occurence?

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

b. The accountant inspects areas where repair costs have been invoiced to ensure repairs have been carried out.

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

d. The accountant compares the amount in the advertising invoice with the advertising quotation