**Core Concept**
Anti-mortem drowning refers to drowning that occurs before death. It is a critical distinction to make in forensic pathology, as it can impact the interpretation of post-mortem findings.

**Why the Correct Answer is Right**
In anti-mortem drowning, the lungs typically exhibit signs of recent gas exchange, such as the presence of water in the airways, pulmonary edema, and the presence of surfactant in the alveoli. This is because the individual was still alive when they inhaled water, allowing for gas exchange to occur. The presence of water in the stomach and small intestine, known as hydro- gastric and hydro- intestinal distension, is also a feature of anti-mortem drowning.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify a feature indicative of anti-mortem drowning. While drowning can cause lung edema, this finding is not exclusive to anti-mortem drowning.
**Option B:** This option is incorrect because it refers to a feature that can be seen in both anti-mortem and post-mortem drowning. The presence of water in the lungs does not necessarily indicate that the individual was alive when they drowned.
**Option C:** This option is incorrect because it refers to a feature that is more commonly associated with post-mortem drowning. The absence of gas exchange in the lungs would suggest that the individual was already dead when they were submerged in water.

**Clinical Pearl / High-Yield Fact**
A key feature to remember when distinguishing between anti-mortem and post-mortem drowning is the presence of water in the stomach and small intestine. Hydro-gastric and hydro-intestinal distension are more likely to occur in anti-mortem drowning, as the individual was still alive and able to swallow water.

**Correct Answer: C. Absence of surfactant in the alveoli is a feature indicative of post-mortem drowning.**