Which clue indicates a suspect sways while balancing during the One-Leg Stand test?

In the context of the One-Leg Stand test, the clue that indicates a suspect sways while balancing is represented by the letter 'S'. During this particular test, the individual is required to stand on one leg while counting aloud, and the primary indicators of impairment include how well they maintain their balance.

When a person sways, it typically suggests a lack of stability, which is a key sign of intoxication. Swaying can occur as the brain's ability to process balance and coordination is affected by alcohol. Thus, the presence of this clue—swaying—strongly indicates potential impairment.

The other options do not pertain to the specific observation of swaying during the One-Leg Stand test, making 'S' the clear indicator of that specific performance issue.