Final Answer:
The primary consideration when selecting a shampoo should be c) pH balance. This factor is crucial for maintaining the natural balance of the scalp and promoting healthy hair.
Step-by-step explanation:
The primary consideration when selecting a shampoo should be c) pH balance. The pH level of a shampoo is crucial because it influences the acidity or alkalinity of the product. The pH balance of the shampoo should be compatible with the natural pH level of the scalp, which is typically slightly acidic (around 4.5 to 5.5). Using a shampoo with an appropriate pH helps maintain the natural balance of the scalp, preventing issues such as dryness or excessive oiliness.
While fragrance (a) and brand popularity (b) can be important for personal preferences and trust in a product, they are secondary considerations compared to the pH balance. Color (d) is generally not a critical factor in the effectiveness or suitability of a shampoo for individual hair and scalp needs.