Which phrase most establishes tension?

A forest of mixed growth somewhere on the eastern spurs of the carpathians
As though he waited for some beast of the woods to come within range of his vision
Ulrich von gradwitz patrolled the dark forest in quest of a human enemy
A man stood one winter night watching and listening

As though he waited for some beast of the woods to come within range of his vision

The phrase "Ulrich von Gradwitz patrolled the dark forest in quest of a human enemy" most establishes tension.

The phrase that most establishes tension is "Ulrich von Gradwitz patrolled the dark forest in quest of a human enemy." This phrase creates a sense of suspense and anticipation by introducing the idea that Ulrich is actively looking for someone who could be a threat to him. To arrive at this conclusion, I analyzed the given phrases and identified the one that includes a specific character (Ulrich von Gradwitz) engaged in a specific action (patrolling the dark forest) for a particular reason (in quest of a human enemy). This combination of factors implies that there is an imminent danger or conflict, generating tension in the scene.