This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Breast, Subject name: Surgery
What procedure is going on here 
Select and explain. 
A. Brachytherapy, B. USG, C. Lateral Pectoral Block, D. Sentinel Lymphnode Biopsy
D: Sentinel Lymphnode Biopsy
Answer: D: Sentinel Lymphnode Biopsy 
Explanation: Ans. (d) Sentinel Lymphnode Biopsy(Ref, Surgery Sixer 3rd Edition Page 275)* Day before surgery or on the same day of surgery inject Technetium 99m Sulfur colloid in the breast parenchyma or around the tumor, this activity can be measured using Gamma probe during surgery.* The node with high activity is Sentinel node.