What is a frequent cause of serious accidents?

You chose all three answers, which is correct. Serious accidents on the road often happen because drivers do not pay enough attention to other traffic, follow the vehicle in front too closely, or fail to adjust their speed to the situation, such as weather, traffic, or road conditions. German traffic rules emphasize defensive driving: always observe your surroundings, keep a safe distance, and drive at a speed that suits the current conditions. Recognizing these risks helps prevent dangerous situations and accidents.