Most fatal accidents are primarily caused by which of the following?

Inattentiveness is a leading cause of fatal accidents because it encompasses a range of distractions that can impair a driver's ability to react to road conditions and traffic signals. Distractions might include using a mobile phone, adjusting the radio, or engaging in conversation with passengers. When drivers are not fully focused on the task of driving, their reaction times slow down, and they may fail to see critical hazards or changes in traffic. This lack of attention significantly increases the risk of collisions, making it a predominant factor in many fatal accidents.

While speeding, DUI, and poor weather conditions are certainly serious contributors to accidents, inattentiveness involves a broader spectrum of behaviors that can affect any driver at any time, regardless of conditions or compliance with speed limits and laws. Hence, it’s crucial for drivers to remain vigilant and minimize distractions whenever they're behind the wheel.