Which characteristic of offense is characterized by taking the enemy by surprise?

The characteristic of offense that is defined by taking the enemy by surprise is aptly identified as surprise. In military tactics, surprise refers to the ability to engage an adversary without their prior knowledge, allowing forces to seize the initiative and create chaos within their ranks. The element of surprise can significantly impact the effectiveness of an operation, as it forces the enemy to react rather than act, often leading to a breakdown in their planned responses. This characteristic is crucial in achieving tactical advantages, disrupting defenses, and maximizing the effectiveness of offensive operations.

While concentration, tempo, and audacity are all important elements of offensive operations, they don't specifically focus on the aspect of surprising the enemy. Concentration involves the massing of combat power at the decisive point, tempo relates to the speed and rhythm of operations, and audacity refers to boldness in planning and execution. However, the essence of achieving surprise lies solely in the ability to catch the enemy off guard, which makes it the correct answer to the question regarding the specific characteristic of offense.