**Core Concept**
The question pertains to the epidemiology and pathophysiology of scabies, a skin infestation caused by the mite Sarcoptes scabiei var. hominis. The average number of adult female mites on an individual with scabies is a critical factor in understanding the disease's severity and transmission.

**Why the Correct Answer is Right**
The correct answer is 12, which reflects the typical burden of adult female mites on an individual with scabies. This is because the common form of scabies is characterized by a relatively low number of mites, usually fewer than 20. The female mites are responsible for laying eggs and perpetuating the infestation. The average number of 12 mites is a key factor in determining the severity of the disease and guiding treatment decisions. It is essential to note that the number of mites can vary depending on the individual's immune status and the presence of any secondary bacterial or fungal infections.

**Why Each Wrong Option is Incorrect**
**Option A:** Averaging 2 mites would be an underestimation of the typical burden, as it would not accurately reflect the severity of the disease.
**Option C:** 16 mites is still within the range of possible values, but it is not the average number commonly cited in medical literature.
**Option D:** 24 mites is an overestimation and would be more characteristic of a severe or crusted scabies case.

**Clinical Pearl / High-Yield Fact**
It is crucial to remember that the number of mites on an individual can vary greatly, and the average value of 12 should not be taken as a hard and fast rule. Factors such as the individual's immune status and the presence of secondary infections can significantly impact the number of mites present.

**✓ Correct Answer: B. 12**