Answer : 4. "Truculent"
Explanation :

The most appropriate synonym for "pugnacious" is "truculent." Both words describe a disposition or attitude of being inclined to quarrel or engage in conflict. The other options— "succulent" (juicy or tender), "germane" (relevant), and "sagacious" (wise)— have different meanings and do not convey the same sense of aggressiveness as "pugnacious" and "truculent."