## **Core Concept**
The development of the pancreas and the onset of insulin secretion are critical in fetal development, particularly in glucose metabolism. Insulin plays a vital role in regulating blood glucose levels and promoting growth and development. The pancreas starts to develop early in embryonic life.

## **Why the Correct Answer is Right**
Insulin secretion in the fetus begins around the 7th to 8th week of gestation. This is a crucial period when the pancreas starts to mature, and the islet cells, specifically the beta cells within the islets of Langerhans, start to produce insulin. By around 11-12 weeks of gestation, the fetal pancreas is capable of producing insulin in response to glucose.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because it does not specify a timeframe that aligns with the initiation of insulin secretion.
- **Option B:** This option is incorrect because it suggests a later timeframe than when insulin secretion actually begins.
- **Option D:** This option is incorrect because it suggests an even later timeframe than option B.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that by the second trimester, the fetus's pancreas is actively producing insulin, which is essential for fetal growth and development. This insulin production is also a critical factor in the regulation of fetal glucose levels.

## **Correct Answer:** C. 11-12 weeks.