**Core Concept**
The Bertillon system, also known as anthropometry, is a method of identifying individuals based on their physical measurements. This system was developed by Alphonse Bertillon in the late 19th century and is used in forensic medicine to classify and identify individuals. Anthropometry involves taking precise measurements of various body parts, such as the length of the head, arm span, and fingers.

**Why the Correct Answer is Right**
The Bertillon system is a systematic method of identifying individuals through precise measurements, which helps to differentiate between individuals with similar physical characteristics. The system involves taking measurements of various body parts, including the length of the head, arm span, and fingers, to create a unique profile for each individual. This profile is then used to identify individuals in forensic investigations. The Bertillon system is based on the principle that no two individuals have the same physical measurements, and by taking precise measurements, investigators can create a unique identifier for each individual.

**Why Each Wrong Option is Incorrect**
**Option B:** Dactylography, also known as fingerprinting, is a method of identifying individuals through the unique patterns found on their fingertips. While dactylography is a widely used method of identification, it is not part of the Bertillon system.

**Option C:** Dentition refers to the arrangement and development of teeth in an individual's mouth. While dentition can be used as a means of identification, it is not part of the Bertillon system.

**Option D:** Nuclear sexing is a method of determining an individual's sex through the analysis of their DNA. While nuclear sexing is a powerful tool in forensic medicine, it is not related to the Bertillon system.

**Clinical Pearl / High-Yield Fact**
It is essential to note that the Bertillon system was widely used in the late 19th and early 20th centuries but has largely been replaced by more advanced methods of identification, such as fingerprinting and DNA analysis. However, the principles of anthropometry remain an essential part of forensic medicine and are still used in certain situations where more advanced methods are not available.

**✓ Correct Answer: A. Anthropometry**