Final answer:
Defensive fortifications are not an offensive strategy; they are meant to protect and maintain a position. Offensive strategies like Blitzkrieg, guerrilla warfare, and attrition involve proactive actions to attack and destabilize the enemy. Option d.
Step-by-step explanation:
Among the principal offensive strategy options listed, d) Defensive fortifications is not one of them. Offensive strategies are proactive measures taken to attack the enemy and gain an advantage. To name a few:
Blitzkrieg: This strategy involved quick, coordinated attacks by air and ground forces, aiming for rapid offensives that could immediately disable an enemy nation's military capabilities.
Guerrilla warfare: A form of irregular warfare where small groups use military tactics, such as ambushes and raids, in the countryside or urban areas.
Attrition: This is a strategy of wearing down the enemy to the point of collapse through continuous losses in personnel and material.
In contrast, strategic defensive fortifications, such as the use of trenches in World War I, are designed to protect and maintain one's position rather than to take the offensive.
So Option d.