question: Why can tUAV (tethered UAV) sustain heavier payloads compared to uUAVs (untethered UAVs)? option 1: tUAVs have a stable energy resource through a tether. option 2: tUAVs have more processing units compared to uUAVs. option 3: tUAVs have higher-altitude hovering capabilities compared to uUAVs. option 4: tUAVs have stronger communication with ground stations compared to uUAVs. option 5: None of the above. 