Final answer:
A new Site Controller candidate must be at least 18 years of age and have completed a minimum of 24 hours of on-site training.
Step-by-step explanation:
A new Site Controller candidate must be at least 18 years of age and have completed a minimum of 24 hours of on-site training. This means that the candidate must meet both criteria in order to be eligible for the position. If the candidate is less than 18 years old or has not completed the required training hours, they would not qualify as a Site Controller candidate.