**Core Concept**
The question is testing the understanding of the risk factors associated with hernia development in various populations. Hernia occurs due to a combination of factors including increased intra-abdominal pressure, muscle weakness, and anatomical defects. The populations' susceptibility to hernia development varies based on their physical characteristics, lifestyle, and occupation.

**Why the Correct Answer is Right**
The correct answer is related to the anatomical and physiological factors that contribute to the risk of hernia development. For instance, individuals with increased intra-abdominal pressure, such as pregnant women or those with chronic cough, are at higher risk of developing hernia. Similarly, individuals with muscle weakness, such as those with chronic diseases like diabetes or those who are malnourished, are also at higher risk.

* **Option A:** Individuals working in heavy manual labor jobs are at higher risk of developing hernia due to increased intra-abdominal pressure and muscle strain. This option is incorrect because it is not the population with the least risk of hernia.
* **Option B:** Individuals with a family history of hernia are at higher risk of developing hernia due to genetic predisposition. This option is incorrect because it is not the population with the least risk of hernia.
* **Option C:** Individuals with a high body mass index (BMI) are at higher risk of developing hernia due to increased intra-abdominal pressure. This option is incorrect because it is not the population with the least risk of hernia.

**Clinical Pearl / High-Yield Fact**
It is essential to note that certain populations are at higher risk of developing hernia, including pregnant women, individuals with chronic cough, and those with muscle weakness. A thorough medical history and physical examination are crucial in identifying individuals at risk of hernia development.

**Correct Answer:** D.