Ans. c. Lack of differentiationRef: Robbins and Cotran Pathologic Basis of Disease 9th Ed; Page No-269Cellular ChangesHyperplasia: Increase in number of cells. May be a risk factor for future malignancy (e.g. to endometrial hyperplasia) but not considered premalignant.Hypertrophy: Increase in size of cells.Atrophy: Decrease in tissue mass due to increase in size and/or number of cells. Causes include disuse, denervation, loss of blood supply, loss of hormonal stimulation, poor nutrition.Dysplasia: Disordered, non-neoplastic cell growth. Term used only with epithelial cells. Mild dysplasia is usually reversible; severe dysplasia usually progresses to carcinoma in situ.Metaplasia: Replacement of one cell type by another. Usually due to exposure to an irritant, such as gastric acid or cigarette smoke. Reversible if the irritant is removed but may undergo malignant transformation with persistent insult (e.g. Barrett esophagus - esophageal adenocarcinoma).Neoplasia: Uncontrolled, clonal proliferation of cells. Can be benign or malignant.Anaplasia: Complete lack of differentiation of cells in a malignant neoplasm.Differentiation The degree to which a malignant tumor resembles its tissue of origin:Well-differentiated tumors (often less aggressive) closely resemble their tissue of origin.Poorly differentiated tumors (often more aggressive) look almost nothing like their tissue of origin.