This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General surgery, Subject name: Surgery
In the Clatke&;s level of tumor invasion for malignant melanoma level 3 refers to 
Select and explain. 
A. All tumar cells above basement membrane, B. Invasion into reticular dermis, C. Invasion into loose connective tissue of papillary dermis, D. Tumor cells at junction of papillary and reticular dermis
D: Tumor cells at junction of papillary and reticular dermis
Answer: D: Tumor cells at junction of papillary and reticular dermis 
Explanation: .Staging of Malignant Melanoma (It is older staging system) IA: Thickness less than 0.75 mm. IB: Thickness between 0.76 to 1.5 mm. IIA: Thickness between 1.51 to 4.0 mm. IIB: Thickness more than 4.0 mm. IIIA: Any of the above + nodes less than 3 cm. IIIB: Any of the above + nodes more than 3 cm. IV: Any of the above + any node + M1 (distant spread) ref:SRB;s manual of surgery,ed 3,pg no 262