Final answer:
For dry brittle hair, a pH-balanced shampoo is recommended to maintain the hair's natural pH level and prevent further damage, while acid balanced shampoos could also be beneficial by helping to lock in moisture.
Step-by-step explanation:
For dry brittle hair, the recommended type of shampoo would be c) pH-balanced. This is because pH-balanced shampoos are formulated to maintain the hair's natural pH level, which is slightly acidic, typically around 4.5 to 5.5. Using highly alkaline shampoos can strip the hair of its natural oils, making it more brittle and prone to damage. Acid balanced shampoos could also be beneficial as they help to close the hair's cuticle, locking in moisture and improving shine. However, the term acid balanced might refer to a specific range within the acidic pH, which could be more appropriate for hair that is not too brittle, whereas pH-balanced could refer to a product designed to match the hair's natural pH level.