What are the common signs of seborrheic dermatitis?

Seborrheic dermatitis is characterized by greasy, scaly patches that are commonly found on the scalp, face, and other regions of the body where sebaceous (oil-producing) glands are prominent. These patches may appear yellow or white and can be associated with redness in the surrounding skin. The condition is often seen in areas such as the scalp (where it may present as dandruff), the nasolabial folds, and behind the ears.

In contrast to the other options, which describe different skin conditions, the signs of seborrheic dermatitis specifically highlight the oily nature and scaling that distinguish it from other dermatologic issues. For instance, dry, cracked skin might be indicative of eczema or psoriasis, while red, inflamed patches with blisters could refer to contact dermatitis or other inflammatory conditions. Pale, smooth lesions are characteristic of certain conditions like vitiligo or certain types of tinea, which are not related to seborrheic dermatitis at all. Thus, the signs described in the correct answer reflect the distinctive features of seborrheic dermatitis.