**Core Concept**
Primordial germ cells (PGCs) are the earliest identifiable precursor cells to gametes in the developing embryo. They migrate to the gonadal ridges and eventually give rise to either oogonia or spermatogonia, depending on the sex of the individual.

**Why the Correct Answer is Right**
The correct answer is derived from the epiblast, specifically a subset of epiblast cells that express specific markers such as BLIMP1 (B lymphocyte-induced maturation protein-1) and PRDM14 (PRDI-BF1-RIZ1 homolog). These cells undergo a series of complex cellular and molecular events, including the formation of the germ plasm, which ultimately leads to the specification and migration of PGCs to the gonadal ridges.

**Why Each Wrong Option is Incorrect**
* **Option A:** This is incorrect because while the epiblast is indeed involved in the development of other germ layer derivatives, the specific subset of epiblast cells that give rise to PGCs is distinct and requires specific molecular markers.
* **Option B:** This is incorrect because the mesoderm is involved in the development of connective tissue, muscles, and other structures, but it is not directly involved in the derivation of PGCs.
* **Option C:** This is incorrect because the ectoderm is involved in the development of the nervous system, skin, and other external structures, but it is not directly involved in the derivation of PGCs.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that PGCs are the earliest identifiable precursor cells to gametes and that their specification and migration are critical for the development of the reproductive system.

**Correct Answer:** C. The ectoderm.