Which of the following is a common defensive control measure?

Establishing a battle handover line is a crucial defensive control measure as it delineates the boundary between two units, particularly during transitions in combat operations. This measure ensures continuity of operations and security while facilitating the effective transfer of responsibility for a specific area of the battlefield. In defensive strategy, clear lines of control are necessary to maintain situational awareness, prevent gaps in defense, and coordinate efforts between units.

While the other options, such as building offensive barriers and designating retreat paths, play important roles in broader tactical operations, they do not represent standard defensive control measures like the battle handover line does. Developing air support plans can enhance defensive capabilities but is more about coordination and support rather than a defined measure of control over the defense itself.