**Core Concept**
Gastric lavage is a procedure used to remove contents from the stomach, often in cases of poisoning. However, its use can be limited by certain conditions that pose a risk to the patient. The underlying principle being tested here is the contraindications to gastric lavage in poisoning.

**Why the Correct Answer is Right**
The correct answer is related to the risk of aspiration of stomach contents into the lungs, which can cause chemical pneumonitis. This is particularly concerning in cases of poisoning with corrosive substances, such as hydrocarbons, which can cause severe damage to the lungs if aspirated. Gastric lavage can dislodge these substances and increase the risk of aspiration.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is likely incorrect because gastric lavage is not contraindicated in poisoning with most medications, such as analgesics or sedatives. While caution is advised, the risk of aspiration is generally lower with these types of substances.

**Option B:** This option may seem plausible, but gastric lavage is actually contraindicated in poisoning with corrosives due to the risk of aspiration. However, the correct answer is not related to corrosives.

**Option D:** This option is incorrect because gastric lavage is not contraindicated in poisoning with most substances due to the risk of encephalopathy. While encephalopathy can be a concern in cases of poisoning, it is not the primary reason for contraindicating gastric lavage.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that gastric lavage should only be performed in a setting where endotracheal intubation and suctioning can be readily performed, to minimize the risk of aspiration. This is particularly important in cases of poisoning with substances that can cause chemical pneumonitis.

**Correct Answer:** C. Corrosives