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A
How shiny the hair is
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B
The hair's ability to stretch and return to its original length without breaking
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C
The hair's color depth
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D
The scalp's oiliness
Why this is the answer
Elasticity refers to the hair's ability to stretch and then return to its original shape without breaking. Hair with good elasticity is healthy and resilient; hair with poor elasticity is weak, may stretch and not recoil, and can break or be damaged during services. Wet hair normally stretches more than dry hair. Poor elasticity is a caution sign before chemical services, which can further stress the hair. Assessing elasticity helps the cosmetologist judge whether the hair can safely undergo a given service.
Source: Hair Care — Elasticity