What type of bond is broken during the perming process?

The type of bond that is broken during the perming process is disulfide bonds. In hair, these bonds are responsible for the hair's shape and structure, linking the sulfur atoms in the amino acid cysteine. When hair is permed, an alkaline solution often containing ammonium thioglycolate is applied to break these disulfide bonds, allowing the hair to be reshaped around a curling rod.

Once the disulfide bonds are broken, the hair can take a new form. After the hair is set in the desired curl pattern, a neutralizing solution is applied, which reforms the disulfide bonds in their new configuration, effectively locking in the curl. This is why understanding the role of disulfide bonds is crucial in the perming process and why it is the correct answer to the question.