Final answer:
Herodotus confirmed our confidence in the rest of the narrative through his use of primary sources.
Step-by-step explanation:
One action of Herodotus that confirms our confidence in the rest of the narrative is his use of primary sources. Herodotus traveled and read sources to gather information about foreign lands and cultures, and he examined contemporary accounts of events. This use of primary sources is a defining characteristic of history as an academic discipline, and it lends credibility to Herodotus' narrative.