When must you stop for a pedestrian at a crosswalk?

You must always yield to pedestrians in any marked crosswalk, which makes this answer the correct choice. This rule is vital for ensuring the safety of pedestrians, who may have the right of way, regardless of whether there are traffic signals present. By allowing pedestrians to cross safely, you contribute to a more organized and secure road environment.

The rationale for yielding to pedestrians at marked crosswalks is rooted in traffic laws that prioritize pedestrian safety. These laws are designed to protect those who are walking, as they are more vulnerable in the event of a collision. Therefore, always stopping for pedestrians demonstrates respect for their rights and promotes a culture of safety on the roads.

Certain other options might suggest conditions under which you would stop for pedestrians, but it's essential to remember that yielding to pedestrians at crosswalks is a fundamental aspect of driving responsibility, irrespective of the presence of traffic signals or the actions of the pedestrian.