Final answer:
To keep the venipuncture site sterile, the cleaner should be allowed to air dry without interference.
Step-by-step explanation:
When preparing an arm for venipuncture, it is essential to allow the cleaner to air dry. This is the recommended method rather than using a cotton ball, blowing on it, or using a fanning motion. Allowing the cleaner to evaporate on its own ensures that the area remains as sterile as possible and reduces the risk of introducing any additional contaminants to the site.