## Core Concept
Gustafson's method is a technique used in forensic odontology. It helps in estimating the **post-mortem interval (PMI)**, which is the time elapsed since death occurred. This method involves assessing various physical and chemical changes in teeth.

## Why the Correct Answer is Right
The correct answer, **age of the deceased**, is related to Gustafson's method because this technique involves evaluating certain changes in teeth that occur over time. These changes include **attrition**, **parodontosis**, **root resorption**, **cementum apposition**, **translucency of the root**, and **secondary dentin formation**. By assessing these factors, forensic experts can estimate the age of the deceased.

## Why Each Wrong Option is Incorrect
* **Option A:** This option is incorrect because Gustafson's method does not directly determine the **sex of the deceased**. While certain skeletal and dental characteristics can be used to estimate sex, Gustafson's method focuses on age estimation.
* **Option B:** This option is incorrect as Gustafson's method is not primarily used for **identification of the deceased**. Identification involves comparing dental records or other unique identifiers, not estimating age through Gustafson's method.
* **Option C:** This option might seem plausible since Gustafson's method involves dental changes, but it is not used for **determining the cause of death**. The cause of death is determined through autopsy and pathological examination.

## Clinical Pearl / High-Yield Fact
A key point to remember is that Gustafson's method provides an estimate of age that can be helpful in forensic investigations. However, its accuracy can be influenced by various factors such as **environmental conditions** and **genetic variability**. This method is considered more reliable when used in conjunction with other forensic techniques.

## Correct Answer Line
**Correct Answer: D. age of the deceased**