What are the two types of defense operations?

The correct response identifies the two primary types of defense operations as area and mobile.

Area defense focuses on holding a specific territory against an enemy's advance, emphasizing strong positional defense with fortifications and prepared defensive measures. This type of operation is often conducted to protect critical assets or to control specific geographic locations.

Mobility is critical in mobile defense, where forces are deployed to maneuver flexibly against the enemy. This approach incorporates active engagement tactics, such as counter-attacks and flanking maneuvers, allowing for a more dynamic response to enemy actions.

The other choices, while having legitimate concepts, do not accurately classify defense operations. Static and dynamic are terms that may describe certain characteristics within a defense but do not cover the broad operational concepts. Similarly, offensive and defensive represent opposing strategies, while field and fortified refer to types of placements rather than overarching categories of defensive strategy.