Which of the following is premalignant condition

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