**Core Concept**
The morula is an early stage in the development of the embryo, consisting of a compact cluster of cells. As the morula develops, it undergoes compaction and differentiation, leading to the formation of the embryo proper. This process involves significant changes in cell morphology and organization.

**Why the Correct Answer is Right**
The embryo proper is derived from the inner cell mass (ICM) of the morula. The ICM is a group of cells that remains undifferentiated and undergoes proliferation to form the embryoblast. The embryoblast then differentiates into the three primary germ layers: ectoderm, endoderm, and mesoderm, which give rise to all tissues and organs in the body. The ICM is crucial for the development of the embryo proper, as it provides the cells necessary for gastrulation and the formation of the germ layers.

**Why Each Wrong Option is Incorrect**
* **Option A:** The trophectoderm is actually the outer layer of cells in the morula, which plays a key role in implantation and the formation of the placenta, but it does not give rise to the embryo proper.
* **Option B:** The blastocoel is a fluid-filled cavity that forms within the morula, but it is not a source of cells for the embryo proper.
* **Option C:** The morula itself is not a specific part that gives rise to the embryo proper, but rather a stage in the development of the embryo.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the inner cell mass (ICM) of the morula gives rise to the embryo proper, while the trophectoderm forms the placenta and other supporting tissues.

**Correct Answer: C. The morula itself is not a specific part that gives rise to the embryo proper, but rather a stage in the development of the embryo.