**Core Concept**
Putrefaction is a complex process involving the breakdown of tissues by microorganisms, leading to the characteristic signs of decomposition. The rate and sequence of putrefaction are influenced by various factors, including temperature, oxygen availability, and the presence of bacteria.

**Why the Correct Answer is Right**
The correct answer is the organ that is resistant to putrefaction due to its high concentration of lipids and its relatively low bacterial load. The brain, being a lipid-rich organ, undergoes putrefaction relatively slowly compared to other organs. This is because the lipids in the brain inhibit the growth of bacteria, thus slowing down the putrefaction process.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the stomach, being an acidic environment, is actually one of the first organs to undergo putrefaction. The acidic pH of the stomach inhibits bacterial growth, but the presence of partially digested food and enzymes also contributes to the rapid breakdown of tissues.
**Option B:** This option is incorrect because the small intestine, although rich in nutrients, undergoes putrefaction relatively quickly. The small intestine's high bacterial load and the presence of partially digested food contribute to its rapid breakdown.
**Option C:** This option is incorrect because the liver, although an essential organ, undergoes putrefaction relatively quickly. The liver's high concentration of water and its rich blood supply make it an ideal environment for bacterial growth.

**Clinical Pearl / High-Yield Fact**
Remember that putrefaction is a complex process influenced by multiple factors, including temperature, oxygen availability, and the presence of bacteria. The brain, being a lipid-rich organ, is relatively resistant to putrefaction.

**Correct Answer:** C. The liver.