Final answer:
The heads-up Cervantes' novel Don Quixote, bystanders and guards often react to Don Quixote's challenges with confusion, amusement, and a perception of him being delusional or mad. Direct reactions from guards to his challenges are not described in the provided texts, but the overall tone suggests a mix of disbelief and mockery from those who witness his antics.
Step-by-step explanation:
The specific scene where Don Quixote challenges guards is not detailed in the provided reference material. However, in many instances in Miguel de Cervantes's novel Don Quixote, when Don Quixote challenges others or confronts what he perceives as giants (which are indeed windmills), the people who witness his actions, including any guards, often react with a mixture of amazement, confusion, and sometimes amusement. They see Don Quixote as a deluded simpleton, engaging in absurdities due to his misguided belief that he is living out the life of a chivalric knight.
In more general terms regarding the novel, bystanders often consider Don Quixote mad because of his challenges against imaginary foes and his outdated sense of chivalry. This results in a range of reactions, from trying to calm him down to mocking him or simply observing his folly from a distance. The reactions can sometimes also be hostile if Don Quixote interrupts important activities or poses a direct challenge to the authority of guards or officials.