Final answer:
Guanidine hydroxide relaxers are true to cause less scalp irritation compared to other hydroxide relaxers while straightening the hair.
Step-by-step explanation:
The statement that guanidine hydroxide relaxers straighten the hair completely, with less scalp irritation than other hydroxide relaxers, is True. Guanidine hydroxide is considered a less harsh alternative to other relaxers such as sodium hydroxide. It is typically marketed to those with sensitive scalps or who have experienced discomfort with other relaxers. Despite this, it's important to note that any chemical relaxer can potentially cause irritation or damage if used improperly.