Question: During a Mobile Terminated NIDD procedure, if the SCEF receives a MT-Data-Answer with a failure cause indicating 'UE cannot be found', what action shall the SCEF take regarding the UE's bearer contexts?
Option 1: The SCEF shall update all the bearer contexts of this UE to a dormant state.
Option 2: The SCEF shall delete all the bearer contexts of this UE and must notify the Operation and Maintenance network element.
Option 3: The SCEF shall delete all the bearer contexts of this UE and may notify the Operation and Maintenance network element.
Option 4: The SCEF shall ignore the failure cause and await further NIDD Submit requests.
Explanation: This is because, according to the specified procedure for handling a 'UE cannot be found' failure cause during Mobile Terminated NIDD, the SCEF is required to delete all bearer contexts associated with the UE. Additionally, it has the discretion (may) to notify the Operation and Maintenance network element, rather than being mandated to do so (must). This aligns with efficient resource management and optional notification for operational oversight.