What condition must be met regarding skid tests to determine which result to use?

To determine the appropriate result from skid tests, the condition is that the lowest result must be chosen. This is because skid tests are often used in accident investigation to determine stopping distances and the conditions of the roadway at the time of the incident. The lowest skid result presents a more conservative estimate of the vehicle's braking capability under the worst conditions, which is crucial for safety assessments and legal considerations.

By using the lowest result, investigators can account for variances in surface conditions, tire performance, and other factors that may affect braking distance. This approach ensures that the data reflects the most cautious scenario, which is essential when evaluating the factors that contributed to an accident. The other options, such as averaging results or noting all results, do not prioritize the safety-focused analysis that's necessary in these evaluations.