Final answer:
Chemical relaxers have the strongest ingredient used in straightening the hair.
Step-by-step explanation:
The type of relaxer that has the strongest ingredient used in straightening the hair is chemical relaxers.
Chemical relaxers contain strong alkaline or acidic ingredients that break and reform the disulfide bonds in the hair, resulting in straightening.
One common ingredient used in chemical relaxers is sodium hydroxide, also known as lye. This type of relaxer is highly effective in straightening the hair, but it should be used with caution and proper safety measures.
Hence, Chemical relaxers have the strongest ingredient used in straightening the hair.