**Core Concept**
Pearson's formula is a method used to estimate the height of an individual based on the length of their long bones. It relies on the correlation between the length of long bones and the overall stature of an individual.

**Why the Correct Answer is Right**
In Pearson's formula, the length of the long bone is multiplied by a specific factor to estimate the height. For the radius, a commonly used factor is 3.27. This factor is derived from the correlation between the length of the radius and the height of the individual. The formula is used in forensic anthropology and orthopedics to estimate the height of individuals from their skeletal remains.

**Why Each Wrong Option is Incorrect**
**Option A:**
*No information provided*.

**Option B:** This option is incorrect because the factor used for the radius in Pearson's formula is not 2.5.

**Option C:** This option is incorrect because the factor used for the radius in Pearson's formula is not 4.1.

**Option D:** This option is incorrect because the factor used for the radius in Pearson's formula is not 2.1.

**Clinical Pearl / High-Yield Fact**
Pearson's formula is a useful tool in forensic anthropology to estimate the height of individuals from their skeletal remains, especially when other methods are not feasible.

**Correct Answer: B. 2.5**