**Core Concept**
Porto-caval anastomosis refers to the communication between the portal venous system and the systemic venous circulation, bypassing the liver's detoxifying and metabolic functions. This pathophysiological phenomenon occurs due to the breakdown of the normal liver-portal circulation axis.

**Why the Correct Answer is Right**
The most significant porto-caval anastomosis is located between the superior mesenteric vein (which carries blood from the small intestine) and the splenic vein (which carries blood from the spleen and stomach), forming the portal vein. However, in the context of the question, the correct answer is related to the anastomosis between the superior mesenteric vein and the inferior vena cava through the inferior mesenteric vein and the left renal vein. This is due to the presence of several anastomotic channels that allow blood to bypass the liver.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the context of the question.
**Option B:** Not a correct description of porto-caval anastomosis.
**Option C:** Not accurate in this context.

**Clinical Pearl / High-Yield Fact**
The presence of porto-caval anastomosis can lead to the development of portal hypertension, which is characterized by increased pressure in the portal venous system. This can result in the formation of varices, ascites, and splenomegaly.

**Correct Answer: D.**