Refer to the exhibit.

In Flow Designer, a Play Message activity must have a valid prompt source. Cisco documents that Flow Designer can play prerecorded audio files or text-to-speech prompts and that TTS content must be configured correctly for Cisco Cloud Text-to-Speech. The exhibit indicates a simple flow that should play a message and then disconnect. If callers hear nothing and the call immediately drops, the most direct cause is that the message node has no valid TTS message configured or the TTS value is invalid. A codec mismatch would typically affect media negotiation more broadly, not only the absence of configured prompt text. A missing audio file would apply if the node used an audio file, but the answer choice points to TTS configuration. Cisco Cloud Text-to-Speech being unavailable would be a service-side outage, which is less consistent with a designer-created flow issue. The local misconfiguration is the invalid or missing TTS message. Reference: Cisco Help, Build and manage flows with Flow Designer; Text-to-Speech in Webex Contact Center.