When the audit work involving other auditors, the principal auditor Make No Reference in th Audit Report in the following circumstances expect

a$)$ When the other auditor audited an immaterial portion of the statements,

b$)$ When the other auditor is well known or closely supervised by the principal auditor,

c$)$ When the principal auditor has thoroughly reviewed the other auditor's work.

d$)$ When the portion of the financial statements audited by the other auditor is material in