An audit firm is testing controls within the purchasing cycle. In which of the following procedures would the firm most likely apply sampling technicques?

A. Risk assessment procedures performed to obtain an understanding of internal control in the purchasing cycle.

B. Test of automated application controls involving check amount limits when effective information technology general controls are present.

C. Analyses of controls to determine the appropriated segregation of duties in the purchasing cycle.

D. Testing of operating effectiveness of controls over authrouzation of purchase orders.