Write a multi-choice question for the following article, with the given choices and answer: Article: You know how much your telephone has changed over the past 10 years? Your car will change even more than that in the next 10 years. One of the biggest changes is that cars will drive themselves. "We certainly have the technology for it now."says Andrew Poliak of automotive technology supplier QNX."We expect self-driving cars to be a mainstream thing between 2020 and 2025." The American company Google has been working on self-driving cars for years. These cars are already on the roads in the United States and are truly self-driving. They have to steering wheels or pedals . Last week, the police ordered one of Google's cars to stop for driving too slowly on a public road. The car was not breaking any law, so no one was punished. Another American company, Tesla, added an "Autopilot" feature to its cars last month. With the Autopilot turned on, the vehicle drives itself. The car will speed up, slow down, _ and drive by itself. You can take over driving any time by turning the steering wheel or touching a pedal. The car uses sensors to know when driveway changing is safe and whether it should speed up or slow down. Tesla Autopilot is made for cross-country driving. It keeps you in the driveway and helps you avoid hitting other cars. It does not work well on local roads, for it will not stop at a red light or stop sign. Reporter Carolyn Nicander Mohr tried the Autopilot feature of a Tesla earlier this month. She had a hard time trusting the car to do what it should do. She thought about disabling the Autopilot feature many times during her trip. She wanted to take control at every bend in the road and hit the brake when the car in front of her slowed down. Yet the car drove perfectly. Other companies are working on self-driving cars, too. Marcedes-Benz, Audi, BMW.Volvo and Toyota all have plans for such vehicles. ,A, B, C, D. Options: A It had no driver. B It went to slowly. C It broke the traffic rules D It had no steering wheel. Answer: B It went to slowly. Question:
Why did the police stop the Google car?