Below are statements or examples related to audit sampling applications. Indicate, using the correct letter, which concept is most closely associated with the statement or example. Each concept may be related to more than one statement or example.
A. Statistical sampling
B. Non-statistical sampling
C. Sampling risk
D. Non-sampling risk.

1). John CPA, selected all invoices over $1,000 and all invoices recorded on the 15th of each month for her sample.
2). Christine, CPA, selected a sample and evaluated the results of his sample using the laws of probability.
3). David CPA, checked to see if any signature was in the credit approval box on a sample of sales orders rather than looking for only authorized signatures.
4). Based on a statistical sample, Benjamin, CPA, concluded the client's control was functioning effectively when the deviation rate in the population was actually unacceptable.
5). When a client could not produce an invoice for a sample selected by the auditor, the auditor accepted the client's assurance that the invoice contained the appropriate approval.