Which nail condition is characterized by the nail plate separating from the nail bed?

Onycholysis is the correct answer because it specifically refers to the condition where the nail plate becomes detached from the underlying nail bed. This separation can be caused by various factors such as trauma, infections, allergic reactions, or underlying health conditions. In this condition, you may notice the nail lifting away, often starting at the tip and moving towards the cuticle, which can lead to discomfort and make the nail more susceptible to damage.

In contrast, trumpet nail is a term used for a nail condition where the edges of the nail plate curve upwards, resembling a trumpet shape, but it does not involve separation from the nail bed. Fingernail psoriasis involves the appearance of pitting or discoloration on the nails without necessarily causing separation from the bed. A split nail typically refers to a nail that has cracked or torn, rather than being detached from the nail bed. Each of these conditions presents differently than onycholysis, making it clear why onycholysis is the specific condition indicated in the question.