Below are some audit tasks performed by an audit assistant: 1. An audit assistant opened the file of purchase invoices and selected 20 orders as part of tests of controls over occurrence. 2. An audit assistant selected all material receivables balances for receivables circularisation tests. 3. An audit assistant selected every hundredth sales invoice and checked to goods despatched note. Required: Discuss whether the above individual audit task is considered as audit sampling techniques or acceptable audit procedures? Explain your answer.