To determine the correct answer, let's analyze the given options in the context of SA 300, which deals with planning an audit of financial statements.
The audit plan is a critical document that outlines the scope, timing, and approach of the audit, considering the client's business and its environment.
It involves understanding the entity's business, identifying areas of high risk, and determining the appropriate audit procedures to be performed.
The audit plan typically includes matters such as the scope of the audit, materiality, audit procedures for each significant account and disclosure, and the allocation of audit work to team members.
Now, let's examine the options provided:
Option A refers to export sales during the year certificate only, and Option B refers to confirmation letters only.
Both of these options are specific audit procedures that may be included in the audit plan, depending on the client's business and the auditor's risk assessment.
Option D mentions that no UDIN is required to be generated, which is not directly related to the development of an audit plan as per SA 300.
However, the question asks for the description of which of the following matters is not a part of developing an audit plan.
Considering the context of SA 300 and the audit planning process, the development of an audit plan involves understanding the client's business, assessing risks, and determining the overall approach to the audit, rather than focusing on specific audit procedures like export sales certificates or confirmation letters.
Therefore, both export sales during the year certificate and confirmation letters are specific audit procedures that may be part of the audit plan, but they are not the primary focus of developing an audit plan.
Thus, the description of both these matters is not a part of developing an audit plan in the context of SA 300.
Hence, **Option C** is the correct answer.