Which of the following is a method used by Cavalry Scouts to detect enemy movement?

Observation posts and patrol routes are critical methods used by Cavalry Scouts to detect enemy movement. These techniques allow scouts to gather intelligence by monitoring specific areas for signs of activity, positioning themselves in strategic locations that provide a wide view of the terrain. Observation posts enable scouts to observe enemy movements discreetly and relay this information back to their commanders, enhancing situational awareness and enabling timely decision-making.

Patrol routes are also essential as they allow scouts to actively seek out enemy forces, assess their strength, and determine their intentions. By patrolling designated areas, scouts can gather real-time information about the enemy, including troop movements, equipment, and logistical capabilities, which is vital for planning and conducting operations.

In contrast, other choices such as strategic bombing, heavy artillery bombardment, and direct engagement in combat primarily focus on delivering offensive actions rather than reconnaissance and surveillance. These methods are generally more destructive and lack the observational aspect that is crucial for the reconnaissance role of Cavalry Scouts. The emphasis on observation and intelligence-gathering is what distinctly characterizes the role and effectiveness of scouts in military operations.