What describes the seal-off breakthrough phase in PLA counterattack?

• A. Conduct a rapid exploitation with massed armor through the center.
• B. Block the shoulders of the penetration with blocking actions, bring firepower onto the penetrating force, then commit depth defense group from a flank.
• C. Withdraw to reform on the defense line.
• D. Focus all fire on the front line with no maneuver.

Answer: (B)

The seal-off breakthrough phase focuses on containing and stopping a penetrating force by using blocking actions to pin and bound its advance, concentrating fire on the penetrating force to fix and degrade it, then bringing in a depth defense group from the flank to seal the breach. Blocking the shoulders of the penetration prevents the attacker from widening the breach or exploiting its sides, while massed fires neutralize its momentum. Swarming in from the flank with a depth defense group closes the gap behind the initial breach, preventing further escape or reinforcement and turning the penetration into a contained situation that can be destroyed or driven back.

The other options describe actions that don’t align with sealing a breakthrough: exploiting through the center is about capitalizing on a breach, not containing it; withdrawing to reform is a retreat rather than a counterattack; and focusing all fire on the front line with no maneuver neglects the essential flank action and blocking needed to seal the penetrated area.