Multi-choice problem: Continue writing the next sentence in this paragraph:

There's a person walking on stilts on a sidewalk where several cars are parked. He is demonstrating how to walk on stilts. he

OPTIONS:
(a). is using a walking stick to move back and forth on the sidewalk near a curb and railings.
(b). is joined by two other men who also join him in the tutorial.
(c). stops and takes a break.
(d). demonstrates the trick using a real stilt.
(b).