Threats to Auditor Independence Can Come from Various Sources

Threats to auditor independence can come from various sources.Which of these is referred to in the Code of Ethics as a self-interest threat?

A) A loan or guarantee from an officer of an assurance client to the auditor.
B) Undue dependence of the audit firm on total fees from an assurance client.
C) Long association of a senior member of an assurance team with the assurance client.
D) a and b.