The primary authority over the internal audit is?

it has to be option D audit committee

Its (D) Audit Committee

D.

Indeed the audit committee. 

So that the management or even external auditors are not able to force them away from working on shareholder's behalf.

The Internal Audit is authorized by the audit committe.

Senior management & in few hierarchies Audit Committee

correct answer is D

Ans. (d)

it is audit committee (Surely)