Final answer:
Blowdrying maintains the hair shaft length while changing the hairstyle temporarily. The correct choice for what blowdrying does to the hair shaft length is 'c) Maintaining.' Blowdrying alters the hair temporarily, as opposed to permanent waving that chemically changes the hair's structure.
Step-by-step explanation:
When blowdrying the hair, it also loosens and elongates the wave pattern, while maintaining the hair shaft length. Therefore, the correct answer to the question is c) Maintaining. Blowdrying the hair can change the style temporally by altering the alpha-helices and forming new hydrogen bonds, but it does not change the length of the hair shaft itself.
Meanwhile, a permanent wave involves reducing agents disrupting the disulfide bonds and an oxidizing agent, like hydrogen peroxide, to reform these bonds in a new position. This chemically alters the structure of the hair to retain a certain style until the hair naturally grows out, which is different from the temporary styling effects of blowdrying.