What actions should auditors take if they identify control deficiencies at their client? 

a. Assess the severity of those deficiencies.

b. Determine whether and how the preliminary control risk assessment should be modified. 

c. Provide documentation about the effect of the control risk assessment on modifications to substantive procedures. 

d. Actions (a), (b), and (c) are all appropriate. 

e. Only (a) and (c) are appropriate.