A Service Bus message must carry binary payload (e.g., a serialized Protobuf object). How is this stored?

1. A Only string messages are supported
2. B As Base64-encoded JSON property
3. ✓ C In the message Body as a byte array (BinaryData) (correct answer)
4. D As a Base64 string in the message label

Shortcut: Service Bus message bodies are opaque byte arrays (BinaryData/Stream). Applications serialize objects (JSON, Protobuf, Avro) and write the bytes to the body. The ContentType property indicates the format.