**Core Concept**
The origin of the ovary is a critical aspect of embryology, specifically in the development of the female reproductive system. The ovaries arise from the intermediate mesoderm, which is one of the three primary germ layers formed during gastrulation. This process is essential for understanding the embryological development of the female reproductive organs.

**Why the Correct Answer is Right**
The correct answer is derived from the embryological development of the female reproductive system. The ovaries, along with the testes, develop from the genital ridges, which are formed from the intermediate mesoderm. As the embryo develops, the genital ridges differentiate into the gonads, which eventually give rise to the ovaries in females and the testes in males. This process is mediated by a complex interplay of genetic and hormonal signals.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the origin of the ovary is not from the ectoderm, which is the outermost layer of the embryo.
**Option B:** This option is incorrect because the origin of the ovary is not from the endoderm, which is the innermost layer of the embryo.
**Option C:** This option is incorrect because the origin of the ovary is not from the neural crest, which is a group of cells that migrate from the neural tube to various parts of the embryo.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the ovaries develop from the intermediate mesoderm, which is a critical aspect of embryology. Understanding this concept can help in diagnosing and managing conditions related to the female reproductive system.

**Correct Answer: D. Intermediate mesoderm**