**Core Concept:**
The Galstain method is a method used to determine the age of a skeletal specimen, specifically in forensic science to determine the age of a deceased individual. It is based on the fusion of specific bones, which occurs at different ages in males and females. The iliac crest is a commonly used site for this purpose due to its accessibility and the visibility of its fusion events.

**Why the Correct Answer is Right:**
The Galstain method uses the fusion of specific bones to estimate age. In females, the iliac crest fuses at different ages depending on the specific bone. In this case, we are focusing on the fusion of the iliac crest. The correct answer refers to the fusion of the pubic symphysis, which occurs in females around the age of 25-30 years.

**Why Each Wrong Option is Incorrect:**
A. This option is incorrect as it refers to the fusion of the ischium, which occurs at a different age than the pubic symphysis.
B. This option is also incorrect as it refers to the fusion of the iliac wing, which occurs at a different age than the pubic symphysis.
C. This option is incorrect as it refers to the fusion of the pubic symphysis, but at a different age range than the correct answer (25-30 years).
D. This option is incorrect as it refers to the fusion of the iliac wing, but at a different age than the correct answer (25-30 years).

**Clinical Pearl:**
The age estimation using the Galstain method is crucial in forensic medicine and anthropology, allowing for age estimation in cases where direct identification is challenging. Understanding the timing of bone fusion helps in making accurate age estimations for legal and scientific purposes.

**Correct Answer:** D. iliac wing fusion occurs around 10-12 years of age.