This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infant deaths & child abuse, Subject name: Forensic Medicine
Raygat's test is based on: 
Select and explain. 
A. Weight of lung, B. Specific gravity of lung, C. Consistency of lung, D. Volume of lungs
B: Specific gravity of lung
Answer: B: Specific gravity of lung 
Explanation: Hydrostatic test/ Raygat's test: Principle: Specific gravity of lung before respiration is 1.04-1.05 and it becomes 0.94-0.95 after respiration. This makes the respired lung to float. Procedure: Dissect out the fetal lungs & Put into a trough of water and observe. Liver is used as control Inference: If they sink--unrespired lung. If they float--remove them from water, cut into small pieces and then squeeze or compress firmly between sponges, and again put into water. If they sink--unrespired lung. If they float--respired lung. Explanation: Floatation observed for second time is because of residual air that remains in the lungs which cannot be squeezed out by pressing, if the fetus has breathed after bih.