In the sentence, 'The new evidence served to CORROBORATE the witness's account,' CORROBORATE most nearly means:

The context — evidence acting on a witness's account — combined with the word's use suggests CORROBORATE means to confirm or support with additional evidence. If new evidence 'serves to corroborate' an account, it backs it up and makes it more credible. The distractor 'contradict' is the opposite. CORROBORATE is common in legal and investigative contexts, where one piece of evidence strengthens another. Using the sentence's logic — evidence that supports a statement — leads you to the correct synonym 'confirm/support.'