OE

The testimony “is supported by evidence,” so it must be believable. The correct answers are “credible” and “sound,” which both mean believable. “Vociferous” (vehement and insistent) and “antagonistic” (feeling hostile towards) are a pair but do not mean believable. “Fallacious” means false, the opposite of what the blank requires. “Assiduous” describes something that is marked by careful attention or consistently applied effort and does not fit this sentence.