## Core Concept
Alpha-fetoprotein (AFP) is a major plasma protein produced by the yolk sac and the liver during fetal development. It is a tumor marker used in the diagnosis and monitoring of certain cancers, most notably hepatocellular carcinoma and testicular cancer, as well as in prenatal screening for fetal anomalies.

## Why the Correct Answer is Right
The correct answer is related to the characteristics or clinical applications of AFP that are not true. Typically, elevated AFP levels are associated with hepatocellular carcinoma, certain germ cell tumors, and fetal anomalies such as neural tube defects. Without the specific options provided, we can infer that the correct statement about AFP being false would relate to its specificity, sensitivity, or clinical utility that is inaccurately described.

## Why Each Wrong Option is Incorrect
Since the specific options (A, B, C, D) are not provided, let's hypothetically analyze:
- **Option A:** If it states that AFP is elevated in hepatocellular carcinoma, this is true. AFP levels are indeed used as a tumor marker for this condition.
- **Option B:** If it mentions that AFP is used in prenatal screening for neural tube defects, this is also true. Elevated AFP levels in maternal serum can indicate potential neural tube defects in the fetus.
- **Option C:** If it suggests that AFP levels are decreased in cirrhosis, this could be misleading. While liver regeneration and liver function are impaired in cirrhosis, the statement might not directly address common associations or uses of AFP.
- **Option D:** Without the content, if one of these options inaccurately describes a well-established fact about AFP (e.g., its production site, clinical application, or association with diseases), it would be incorrect based on established medical knowledge.

## Clinical Pearl / High-Yield Fact
A key point to remember is that **AFP levels are elevated in conditions like hepatocellular carcinoma and neural tube defects but are decreased in cases of Down syndrome**. This makes AFP a valuable marker in both oncology and prenatal screening.

## Correct Answer: D.