**Core Concept**
Human stem cells are a type of undifferentiated cell that have the ability to differentiate into various cell types and are characterized by their self-renewal and pluripotency. The expression of specific genes and proteins determines the fate of these cells.

**Why the Correct Answer is Right**
Human stem cells express the transcription factor OCT4 (also known as POU5F1), which is a crucial regulator of pluripotency and self-renewal. OCT4 binds to specific DNA sequences, thereby activating the expression of genes involved in cell proliferation and differentiation. The expression of OCT4 is a hallmark of human embryonic stem cells and induced pluripotent stem cells (iPSCs). Additionally, OCT4 is involved in the maintenance of the stem cell niche and the prevention of premature differentiation.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because while human stem cells do express various growth factors such as FGF2 (fibroblast growth factor 2), these factors are not specific markers of stem cell identity.
**Option B:** This option is incorrect because while human stem cells do express various transcription factors such as SOX2 (SRY-box transcription factor 2), SOX2 is not as specific to human stem cells as OCT4 is.
**Option C:** This option is incorrect because while human stem cells do express various surface markers such as CD133 (prominin-1), CD133 is not a specific marker of human stem cells and can be expressed by other cell types as well.

**Clinical Pearl / High-Yield Fact**
It's essential to note that the expression of OCT4 is not exclusive to human stem cells and can be detected in certain types of cancer cells, such as embryonal carcinoma cells. This highlights the importance of using a combination of markers to identify stem cells in a specific context.

**Correct Answer:** C.