Question: What is the primary reason for sending a cause value of 33 in response to a CM SERVICE REQUEST message?
Option 1: The requested service option is temporarily out of order.
Option 2: The MS has no subscription for the requested service option.
Option 3: The PLMN does not support the requested service option.
Option 4: The network cannot identify the call associated with a call re-establishment request.
Explanation: Cause value 33 is sent when the MS requests a service option for which it has no subscription, indicating that the primary reason is related to the MS's subscription status.