Which of the following techniques helps in reducing the chances of being detected during terrain flight?

Nap of the Earth flight is an effective technique designed to minimize detection during terrain flight. This method involves flying at very low altitudes, often close to the contours of the terrain, which allows the aircraft to blend in with the natural landscape. By maneuvering in and out of ground features such as hills, trees, and buildings, the aircraft can take advantage of visual and radar masking, making it much harder for enemy observers or radar systems to detect or track it.

The fundamental principle behind this technique is to enhance the aircraft's stealth capabilities, allowing it to gain tactical advantages in hostile environments. Flying at low altitude, in conjunction with the terrain, significantly reduces the aircraft's radar cross-section and visual footprint, thereby improving its survivability in combat situations.

Other techniques, while they may contribute to overall mission effectiveness, do not emphasize detection avoidance in the same manner as Nap of the Earth flight. High altitude flying is generally more predictable and hence more detectable. Constant fixed speed flying lacks the maneuverability offered by Nap of the Earth strategies, rendering it less effective in engaging with terrain features for avoidance purposes. Finally, operational clarity relates to mission planning and understanding rather than the specific execution of techniques that would help in avoiding detection during the flight.