Which of the following is a symptom of tinea pedis?

Tinea pedis, commonly known as athlete's foot, is a fungal infection that primarily affects the skin of the feet. One of the hallmark symptoms of this condition is scaling on the skin of the feet, which occurs as the fungal infection leads to dryness, flaking, and peeling of the skin. This scaling can range from mild flaking to severe cracking and can sometimes be accompanied by redness or itching.

The other symptoms listed in the choices describe conditions that are associated with different issues. Whitish patches on the nails are more characteristic of a fungal nail infection rather than athlete's foot specifically. Pus formation around the nails typically indicates a bacterial infection, not a fungal one. Lastly, separation of the nail plate from the nail bed is a condition known as onycholysis, which can be caused by various factors, including trauma or infections, but is not a symptom directly associated with tinea pedis.

Therefore, scaling on the skin of the feet is the correct answer as it directly relates to the symptoms exhibited by tinea pedis.