After obtaining an understanding of internal control and assessing control risk, an auditor decided to perform tests of controls. The auditor most likely decided that

a. It would be efficient to perform tests of controls that would result in a reduction in planned substantive tests.

b. Additional evidence to support a further reduction in control risk is not available.

c. An increase in the assessed level of control risk is justified for certain financial statement assertions.

d. There were many internal control weaknesses that could allow errors to enter the accounting system.