The PRIMARY reason an IS auditor performs a functional walkthrough during the preliminary
phase of an audit assignment is to:

A.
understand the business process.

B.
comply with auditing standards.

C.
identify control weakness.

D.
plan substantive testing.

Explanation:

Understanding the business process is the first step an IS auditor needs to perform. Standards do
not require an IS auditor to perform a process walkthrough. Identifying control weaknesses is not
the primary reason for the walkthrough and typically occurs at a later stage in the audit, while
planning for substantive testing is performed at a later stage in the audit.