What is the primary purpose of the Standardized Field Sobriety Test (SFST)?

The primary purpose of the Standardized Field Sobriety Test (SFST) is to assess a person's level of impairment due to alcohol or drugs. This set of tests is designed to provide law enforcement officers with observable evidence of a driver’s ability to operate a vehicle safely. The tests evaluate physical coordination, balance, and cognitive functions which can be significantly affected by substance impairment.

The SFST is a systematic approach that helps in making informed decisions regarding whether an individual is fit to drive. It includes components such as the Horizontal Gaze Nystagmus test, the Walk-and-Turn test, and the One-Leg Stand test, each of which measures different signs of impairment.

The incorrect options do not align with the main focus of the SFST. While fatigue, driving history, and mental state may influence a person's driving abilities, the SFST specifically targets impairment caused by alcohol or drugs, which is critical for ensuring road safety.