Final answer:
Hair should not be pressed when it's wet, as the high heat can cause damage to the weak and susceptible strands. Drying the hair completely before pressing and avoiding pressing when it's dirty are both recommended to prevent damage and product build-up.
Step-by-step explanation:
Under what circumstances should hair not be pressed? The correct answer is c) When it's wet. Pressing hair when it is wet can cause severe damage to the hair strands because wet hair is more fragile and susceptible to breakage. The high heat of pressing tools like flat irons can cause the water in the hair to heat up and create steam, which then leads to weakened hair structure and potential breakage. It is always advised to dry hair thoroughly before using any type of pressing tools. Additionally, other undesirable conditions for pressing hair include when it's damp (as it is still not fully dry) and when it's dirty (as this can lead to product build-up on your pressing tools as well as your hair).