Final answer:
When using a thermal iron on sensitive hair types like tinted, white, or very fine hair, the correct approach is to use a lower iron temperature, pre-test the iron's heat on a damp towel and a strand of hair, not the highest temperature which is false.
Step-by-step explanation:
The question pertains to the proper procedure when using a thermal iron on tinted, white, or very fine hair. Among the provided options, the one that is false is that the highest iron temperature should be used. In practice, a lower iron temperature is employed for such hair types to prevent damage. Additionally, the iron should be closed lightly on a damp towel before curling to dampen the heat, and its temperature should always be tested on a piece of hair prior to the service to avoid scorching.