This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Given Condition is due to a defect in the normal keratinization of the oral mucosa: 
Select and explain. 
A. White sponge Nevus., B. Erythema multiformae., C. Incontinentia pigmenti., D. Systemic sclerosis.
A: White sponge Nevus.
Answer: A: White sponge Nevus. 
Explanation: None