Question: For which UE category is it mandatory to support the logicalChannelSR-ProhibitTimer feature, as specified in the Medium Access Control (MAC) protocol specification?
Option 1: UE Category-M (Machine-Type Communications)
Option 2: UE Category-NB (Narrow Band Internet of Things)
Option 3: UE Category-1 (Wide Area Coverage, Low Complexity)
Option 4: UE Category-0 (Low Complexity, Low Bandwidth)
Explanation: The correct answer is Option 2 because the logicalChannelSR-ProhibitTimer feature support is explicitly mandated for UEs of any UE Category-NB. This category is specifically designed for Narrow Band Internet of Things (NB-IoT) applications, where efficient use of resources and tailored features like this timer are crucial for the intended low-power, wide-area network use cases.