Which of the following tests is considered a standard field sobriety test?

The Horizontal Gaze Nystagmus (HGN) Test is considered a standard field sobriety test because it is scientifically validated and widely accepted as an effective method for assessing a person's level of impairment due to alcohol. This test involves observing the eyes as they track a moving stimulus, typically a pen or a finger, and measuring the involuntary jerking movements (nystagmus) that can occur at certain blood alcohol concentration levels. The presence and degree of these eye movements can indicate the likelihood of impairment, making the HGN a reliable assessment tool for law enforcement officers during DUI investigations.

In contrast, while a Breathalyzer is a common tool for measuring blood alcohol content, it is not classified as a field sobriety test; it is a type of chemical test administered after field sobriety tests have been conducted. Similarly, a pulse check does not provide relevant information regarding impairment and is not a valid assessment method in this context. The walking on a straight line test, while sometimes used in the assessment of sobriety, is not as standardized or validated as the HGN test, which is why it does not fulfill the criteria of a recognized standard field sobriety test on its own.