Which of the following statements concerning control deficiencies is true?

a. The auditor should communicate to management, in writing, all control deficiencies in internal control identified during the audit.

b. All significant deficiencies are material weaknesses.

c. All control deficiencies are significant deficiencies.

d. An auditor must immediately report material weaknesses and signifi- cant deficiencies discovered during an audit to the PCAOB. p-986