**Core Concept**
Von Gierke's disease, also known as type I glycogen storage disease, is a congenital disorder caused by a deficiency in the enzyme glucose-6-phosphatase. This enzyme plays a crucial role in glycogenolysis and gluconeogenesis, allowing glucose to be released from glycogen stores into the bloodstream.

**Why the Correct Answer is Right**
The correct answer is associated with hypoglycemia, as glucose-6-phosphatase deficiency impairs the liver's ability to convert glucose-6-phosphate to glucose, leading to decreased blood glucose levels. This enzyme is specifically involved in the final step of glycogenolysis, where glucose-6-phosphate is converted to glucose. Without this enzyme, glucose remains trapped within the glycogen molecule, leading to hypoglycemia.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because Von Gierke's disease is not primarily associated with lactic acidosis, although it can occur due to the accumulation of glucose-6-phosphate and subsequent increase in lactate production.
* **Option B:** This option is incorrect because Von Gierke's disease is not primarily associated with ketosis, although it can occur due to the body's attempt to compensate for the lack of glucose by breaking down fat for energy.
* **Option C:** This option is incorrect because Von Gierke's disease is not primarily associated with Fanconi syndrome, which is a disorder of proximal tubular function.

**Clinical Pearl / High-Yield Fact**
Von Gierke's disease is characterized by a classic triad of symptoms: hypoglycemia, lactic acidosis, and hepatomegaly due to glycogen accumulation in the liver.

**Correct Answer: C. Fanconi syndrome is a disorder of proximal tubular function.