This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Oral cavity & Oesophagus, Subject name: ENT
Which of the following is premalignant condition 
Select and explain. 
A. Chronic glossitis, B. Hyperophic glossitis, C. Submucous fibrosis, D. Aphthous stomatitis
C: Submucous fibrosis
Answer: C: Submucous fibrosis 
Explanation: SUBMUCOUS FIBROSIS Oral submucous fibrosis (OSF) is a chronic insidious process characterized by juxtaepithelial deposition of fibrous tissue in the oral cavity and pharynx. PATHOLOGY : The basic change is fibroelastotic transformation of connective tissues in lamina propria associated with epithelial atrophy, sometimes preceded by vesicle formation. In later stages, when fibrosis is marked, there is progressive trismus and difficulty to protrude the tongue. Leukoplakia and squamous cell carcinoma may be associated with submucous fibrosis possibly because of common aetiological factors involved. It is a premalignant condition and malignant transforma tion has been seen in 3-7.6% of cases. Ref:- Dhingra; pg num:-220,221