To answer this question, we need to understand the different types of ammunition used by tanks.
A. Smoke shell - A smoke shell is designed to create a smoke screen to obscure visibility on the battlefield. It is not directly related to armor penetration or anti-armor capabilities.
B. High explosive round - A high explosive round is designed to explode upon impact, causing damage to the target area. While it can be effective against various targets, it is not specifically designed for anti-armor purposes.
C. Anti-armor round - A SABOT (Saboted Light Armor Penetrator) round is an anti-armor round. When a tank fires a SABOT round, it means that it is using a type of ammunition specifically designed to penetrate and defeat armored targets. The SABOT round consists of a sub-caliber penetrator encased in a lightweight sabot, which is discarded after leaving the barrel. This design allows for high velocity and armor-piercing capabilities.
D. Cluster munition - Cluster munitions are designed to disperse submunitions over a wide area, targeting multiple smaller targets. They are not specifically designed for anti-armor purposes.
Therefore, the correct answer is C) Anti-armor round. Firing a SABOT round indicates that the tank is using an ammunition specifically designed to penetrate and defeat armored targets.