Which requirement requires using SuiteScript rather than SuiteFlow?

The requirement that necessitates SuiteScript over SuiteFlow is setting the value of a multi-select field. SuiteFlow's native "Set Field Value" action does not support setting or modifying multi-select fields. This is a known platform limitation. Manipulating a multi-select field requires passing an array of internal IDs for the selected options, a task that can only be accomplished programmatically using SuiteScript (e.g., with the record.setValue() method). The other options describe standard processes that are well within the native capabilities of the SuiteFlow engine.

A. Sending a customer survey when clicking a button. This is incorrect. SuiteFlow can be initiated by a user event like a button click and includes a "Send Email" action, which can contain a link to a survey.
B. Creating a custom approval process on Sales Order records. This is incorrect. Creating approval routing workflows with different states (e.g., Pending Approval, Approved) and actions is a primary and fundamental use case for SuiteFlow.
C. Creating a task for the Sales Rep when saving Opportunity. This is incorrect. A workflow can be triggered on record save and use the "Create Record" action to generate a new Task record and assign it dynamically.

1. NetSuite Help Center: SuiteFlow > Workflow Actions > Set Field Value Action. The documentation for this action details the field types it supports, and it does not include the multi-select field type. This limitation necessitates scripting for such operations.

2. NetSuite Help Center: SuiteScript 2.1 > SuiteScript 2.1 API > N/record Module > Record > setValue(options). The API documentation explicitly shows that to set a multi-select field's value, the value parameter must be an Array | Array, confirming this is a programmatic operation.

3. SuiteAnswers (NetSuite's Official Knowledge Base): Answer ID 26951 - Workflow (SuiteFlow) FAQ. This document frequently addresses common limitations. It clarifies that the "Set Field Value" action in a workflow cannot be used to set values for multi-select fields.

4. NetSuite Help Center: SuiteFlow > Workflow Actions > Create Record Action. This documentation confirms that SuiteFlow can be used to create instances of other records, such as Tasks, as part of a workflow process.