Question: When a replying Mobile Station (MS) submits a reply Mobile Originated (MO) Short Message (SM) and a reply path exists, what happens to the reply path after submitting one reply MO SM?
Option 1: The reply path remains available for subsequent reply MO SMs.
Option 2: The reply path is modified to point to a default Service Center (SC).
Option 3: The reply path does not exist anymore after the submission.
Option 4: The reply path is automatically updated to the originating SME.
Explanation: According to specifications, once the replying MS submits one reply MO SM and a reply path exists, the reply path ceases to exist. This ensures efficient management of message routing and delivery in SMS, with subsequent messages following appropriate routing logic based on the absence of a reply path.