Final answer:
Children and older pedestrians are the most at-risk pedestrian groups due to their developmental stage, physical limitations, or sensory impairments. Traffic signals can enhance their safety by facilitating safer crossing times.
Step-by-step explanation:
The pedestrians most at risk are typically those who face greater challenges or have less experience with traffic. Looking at the provided options and considering various factors such as cognitive development, physical ability, and life experience, the group that stands out as the most vulnerable are Option 1: Children and older pedestrians. Children, particularly in the age ranges of 0 to 13, are still developing the cognitive skills needed to judge speed and distance accurately, and may also be less visible to drivers due to their smaller stature. Older pedestrians may have mobility limitations or sensory impairments that can increase their risk. Moreover, installing traffic signals at intersections can significantly improve pedestrian safety by allowing them to cross at appropriate times, reducing the need to navigate amidst moving traffic.