question: What are the four major components of user plane latency in the physical layer? option 1: Time-to-transmit latency, propagation delay, processing latency, and re-transmission time option 2: Time-to-transmit latency, propagation delay, channel capacity, and re-transmission time option 3: Time-to-transmit latency, propagation delay, modulation technique, and re-transmission time option 4: Time-to-transmit latency, propagation delay, channel coding rate, and re-transmission time 