Which zone is described as including frontier defense group, depth defense group, combat reserve group, and cover group?

• A. Frontline Group Zone
• B. Four Primary Defensive Groups
• C. Rear Defense Zone
• D. Depth Defense Group

Answer: (C)

The main idea here is how defense is organized in layers to protect the rear while still allowing flexible responses. The set of groups described—frontier defense, depth defense, cover, and combat reserve—forms a complete rear defense arrangement. Each element plays a distinct role: frontier defense at the forward edge blocks and slows the enemy; depth defense sits behind to further retard and inflict attrition; the cover group protects critical assets and lines of communication within the rear; and the combat reserve group remains as ready forces to reinforce or counterattack as the situation evolves. Together they define and populate a single zone focused on protecting the rear area and sustaining operations, which is why the Rear Defense Zone is the best fit.

Other options refer to specific forward elements or individual groups, not to a zone that unites all four. The frontline or frontier-focused concept describes forward defense, not the broader rear-area structure. The Depth Defense Group is only one component, not the whole zone. The Four Primary Defensive Groups describe the types of groups, not the zone that houses them.