Independence, objectivity, assurance, consulting, value adding, improving operations, helps achieve organizational objectives, systematically disciplined approach, evaluate and improve effectiveness are key terms that Murdock uses to describe what internal audit is and ultimately what operations audit is also.

a. The statement is false because these key terms may also be describing external audit.

b. The statement is true because operations audit is a sub-category of internal audit.

c. The statement is true because internal audit encompasses all its forms regardless of the design or purpose of the types under it like operations audit, management audit, and compliance audit, these still include the key terms mentioned above in its description.

d. The statement is false because though operations audit is a sub-category, its primary purpose is different from internal audit