**Core Concept**
The human body has several anatomical differences between the right and left kidneys, primarily due to the presence of the liver and the duodenum on the right side. These differences affect the position, size, and blood supply of the right kidney compared to the left kidney.

**Why the Correct Answer is Right**
The correct answer is that the right kidney is not preferred over the left for transplantation. This is because the right kidney is generally smaller and has a different blood supply, with the right renal vein draining directly into the inferior vena cava. This anatomical difference makes the right kidney more challenging to transplant, as the surgeon must take extra precautions to avoid damaging the vena cava.

**Why Each Wrong Option is Incorrect**
**Option A:** This statement is incorrect because the right renal vein is actually longer than the left renal vein. The right renal vein has to travel a longer distance to reach the inferior vena cava, which is located below the liver.
**Option B:** This statement is correct. The right kidney is related to the duodenum, which is a part of the small intestine that is located on the right side of the body. The right kidney and duodenum are in close proximity, and the right renal artery passes behind the duodenum.
**Option D:** This statement is correct. The right kidney is generally placed at a lower level than the left kidney due to the presence of the liver and the diaphragm. The liver pushes the right kidney downward, making it lower than the left kidney.

**Clinical Pearl / High-Yield Fact**
When it comes to kidney transplantation, the left kidney is generally preferred over the right kidney due to its larger size and more straightforward blood supply. Surgeons often prefer to transplant the left kidney because it is easier to connect the left renal vein to the external iliac vein.

**✓ Correct Answer: C. Rt kidney is preferred over left for transplantation**