**Core Concept**
Raygat's test is a forensic procedure used to determine the presence of air in the lungs, which is crucial in identifying drowning as the cause of death. This test relies on the principle of density differences between air-filled and non-air-filled lung tissues. The specific gravity of lung tissue is used to determine the presence of air.

**Why the Correct Answer is Right**
The specific gravity of lung tissue is measured by comparing its weight in air to its weight in water. When lung tissue is air-filled, it becomes less dense than water, resulting in a higher specific gravity. This is the basis of Raygat's test, which involves measuring the specific gravity of lung tissue to determine the presence of air. The presence of air in the lungs indicates that the person was alive at the time of drowning and that the drowning was not due to other causes.

**Why Each Wrong Option is Incorrect**
**Option A:** Weight of lung - While the weight of the lung can provide some information, it is not the basis of Raygat's test, which focuses on the density of the lung tissue.
**Option C:** Consistency of lung - The consistency of lung tissue is not a reliable indicator of air presence in the lungs.
**Option D:** Volume of lungs - The volume of the lungs is not directly related to the presence of air in the lungs and is not the basis of Raygat's test.

**Clinical Pearl / High-Yield Fact**
It is essential to note that Raygat's test is not a definitive test for drowning, but it can provide valuable information when combined with other forensic evidence. A specific gravity of lung tissue greater than 1.05 indicates the presence of air in the lungs, suggesting that the person was alive at the time of drowning.

**✓ Correct Answer: B. Specific gravity of lung**