Final answer:
Don Pedro and Claudio initially react to Benedick's challenge with surprise and skepticism in 'Much Ado About Nothing' by William Shakespeare.
Step-by-step explanation:
In William Shakespeare's play 'Much Ado About Nothing,' Don Pedro and Claudio first react to Benedick's challenge with surprise and skepticism. Upon hearing Benedick's challenge to engage in a duel, they cannot believe that Benedick, who is known for his wit and dislike of marriage, would willingly participate in such an event. Their initial reaction is one of disbelief and amusement.