Final answer:
An on-base tool placement will create the smallest diameter of the curl, ensuring a resilient and tight curl due to the maximum tension generated from the hair being fully off the scalp.
Step-by-step explanation:
An on-base (full-base) tool placement will result in the strongest base strength and the smallest diameter of the curl. This method of curling where the hair is wound around the tool with the base of the strand fully off the scalp provides the maximum tension and thus the curl will have the smallest diameter and will be quite resilient.
It's important to consider that the volume and texture achieved will also be influenced by the diameter of the tool used and the technique applied by the stylist.