In SAP Ariba Supplier Management, the process of collecting information directly from an external party, such as a supplier, is managed through questionnaires. An "External Questionnaire" is specifically designed to be sent to suppliers to gather essential data for processes like registration, qualification, or profile updates. Bank account details are a critical piece of supplier profile information, and collecting them via a secure, structured external questionnaire is the standard and recommended practice within the SAP Ariba platform.

A. Internal questionnaire: This is incorrect because internal questionnaires are completed by users within the buying organization to assess or provide information about a supplier, not by the supplier themselves.

C. Internal form: This is incorrect as it is an internal-facing document used for internal processes and requests, not for collecting data from an external entity like a supplier.

D. External form: This is incorrect because "questionnaire" is the specific and standard SAP Ariba terminology for a structured set of questions sent to suppliers for data collection, not "form."

1. SAP Ariba Help Portal, Supplier Management and Configuration Guide: In the section "About Questionnaires," the documentation distinguishes between internal and external types. It states, "External questionnaires are questionnaires that you send to suppliers to gather information about them... for example, as part of a registration or qualification process." This directly supports using an external questionnaire to collect supplier data. (Reference specific to SAP Ariba Cloud version documentation).

2. SAP Ariba Help Portal, Supplier Registration and Qualification Project Management Guide: The section on "Supplier Registration Questionnaires" details how these external documents are the primary mechanism for collecting initial supplier information, which commonly includes company, contact, and banking details. This confirms the use case presented in the question.

3. SAP Ariba Help Portal, Topic ID: ARISUPPLIERMGMTQUESTIONNAIRES: The topic "Internal and external questionnaires" explicitly defines the distinction: "External questionnaires are questionnaires that you send to suppliers to gather information about them. Internal questionnaires are questionnaires that internal users in your organization fill out to provide information about a supplier." This provides a clear definition that validates the correct answer.