## Core Concept
The morula stage is a critical phase in early embryonic development, occurring after the fertilization of an egg and before the formation of a blastocyst. It is characterized by compaction of cells.

## Why the Correct Answer is Right
The morula stage typically consists of 16 cells, which is a result of several cleavage divisions of the zygote without significant growth, leading to a compact cluster of cells. This stage is crucial for the development and differentiation of the embryo.

## Why Each Wrong Option is Incorrect
* **Option A:** 2-4 cells - This represents an earlier stage known as the cleavage stage or zygote stage before reaching the morula.
* **Option B:** 8 cells - This stage is known as the octant stage and occurs before the morula stage.
* **Option D:** More than 32 cells - This would represent a stage closer to or beyond the blastocyst formation.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the morula stage is a transitional phase where the embryo undergoes compaction, which is essential for further development. This usually happens around 3-4 days post-fertilization.

## Correct Answer: C. 16 cells