A patient comes into the clinic complaining of pain in her right eye. On examination, the nurse sees a pustule at the lid margin that is painful to touch, red, and swollen. The nurse recognizes that this is a:

A. Blepharitis: Inflammation of the eyelid margins, typically associated with itching, burning, and crusting, but not localized pustules. B. Dacryocystitis: Inflammation of the lacrimal sac, causing swelling near the inner canthus, not on the lid margin. C. Chalazion: A painless lump or cyst inside the eyelid, not typically painful, red, or swollen at the lid margin. D. Hordeolum (Stye): A stye is a localized infection of a sebaceous gland at the eyelid margin, causing pain, redness, and swelling.