What best captures the meaning of 'truculent'?

The term 'truculent' refers to a disposition that is fierce, aggressive, or eager to fight. It often describes a person or an animal that displays a combative attitude or a tendency to be confrontational. Given this definition, the choice that best captures the meaning of 'truculent' is one that conveys this aggressive nature.

The other options describe characteristics associated with gentleness, friendliness, calmness, and being unruffled, which are antithetical to the concept of being truculent. Therefore, the correct answer encapsulates the essence of 'truculent' by emphasizing fierceness and aggression, aligning perfectly with how it is commonly understood in English vocabulary.