Part A (5 marks) You have obtained an understanding of the audit client's internal controls but noticed the following internal control weakness: The clerk was not aware of the recent change in selling prices. Accordingly, incorrect price was used on sales invoices for billing to customers. Required: a. What is the primary control activity that was absent? (1 marks) b. What is the assertion that has not been met? (1 marks) c. Recommend an internal control to rectify the above weakness. (3 marks)