**Core Concept**
The process of morphogenesis involves the complex interactions of various signaling pathways and transcription factors to regulate the formation and organization of tissues and organs during embryonic development. This intricate process is crucial for the proper development of an organism.

**Why the Correct Answer is Right**
The correct answer is **sonic hedgehog (SHH)**. SHH is a key signaling molecule that plays a vital role in regulating normal morphogenesis during development. It is involved in the formation of various tissues and organs, including the brain, limbs, and gut. SHH signaling is mediated through the Patched receptor and the Gli transcription factors, which ultimately regulate the expression of target genes involved in morphogenesis.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because while WNT signaling is involved in cell fate determination and tissue patterning, it is not the primary regulator of normal morphogenesis during development.
**Option B:** This option is incorrect because BMP signaling is involved in the regulation of cell differentiation and tissue organization, but it is not the primary regulator of normal morphogenesis during development.
**Option C:** This option is incorrect because Notch signaling is involved in cell fate determination and cell-cell interactions, but it is not the primary regulator of normal morphogenesis during development.

**Clinical Pearl / High-Yield Fact**
Morphogenesis is a critical process in embryonic development, and abnormalities in this process can lead to congenital malformations and developmental disorders. Understanding the role of SHH signaling in morphogenesis is essential for the diagnosis and treatment of disorders such as holoprosencephaly and polydactyly.

**Correct Answer:** C.