Which condition presents with a fragile mucosa that blisters with pressure?

The condition that presents with a fragile mucosa that blisters with pressure is indeed associated with Nikolsky's sign. This sign is indicative of certain dermatological and mucosal disorders where gentle pressure or traction on the skin or mucosa causes it to blister or separate. Conditions like pemphigus vulgaris, which is an autoimmune blistering disorder, exhibit this sign, leading to the fragility of the mucosal surfaces.

Other choices do not exhibit this characteristic. Candidiasis is a fungal infection that typically presents with white patches and may cause discomfort, but it does not primarily lead to blistering or a fragile mucosa upon pressure. Leukoplakia, characterized by white patches on the mucous membranes, is mostly associated with an increased risk of malignancy and does not relate to fragile mucosal integrity. Leukoedema presents as a grayish-white mucosal change and is generally a benign condition, not associated with blister formation under pressure.