Final answer:
The correct answer is A) Dandruff, which is characterized by small, white scales on the scalp and hair, and can be treated with over-the-counter shampoos.
Step-by-step explanation:
Small, white scales appearing on the scalp and hair are a sign of dandruff. Dandruff is a common condition that leads to the flaking of the scalp, and it can be treated with over-the-counter dandruff shampoos and steroids in more severe cases. While both psoriasis and seborrheic dermatitis can also cause scaling on the scalp, the scales from psoriasis often have a thick, silvery appearance and are associated with patches of redness and irritation. Seborrheic dermatitis may cause scales that are yellowish and oily, not just white. Tinea capitis, on the other hand, is a fungal infection also known as scalp ringworm, which can cause scaly patches and hair loss. Therefore, the correct answer is A) Dandruff.