A service dog that can guide people through crowds, around obstacles, and stop at crossings is for:

Guide dogs help people with visual impairments and blindness navigate their surroundings. These are the most common service dogs, and they usually are the first example that pops up in our heads when we think about working animals. In the video below, kids meet a Guide Dog and ask all the questions we wouldn't have the nerve to! Check it out to learn more about guide dogs: https://youtu.be/PW2duKZChA8?t=55.

Photo by Lars Christensen from Shutterstock.