**Core Concept**
The Shine-Dalgarno sequence is a conserved nucleotide motif in bacterial mRNA that plays a crucial role in the initiation of protein synthesis. This sequence is located near the start codon (AUG) and is essential for the recruitment of the ribosome to the mRNA.

**Why the Correct Answer is Right**
The Shine-Dalgarno sequence is a purine-rich region that is complementary to the 3' end of the 16S rRNA in the bacterial ribosome. This complementarity allows for the base pairing of the mRNA and the rRNA, thereby facilitating the positioning of the ribosome on the mRNA. The sequence is typically located 8-13 nucleotides upstream of the start codon (AUG) and is essential for the initiation of translation.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the Shine-Dalgarno sequence is not located near the poly-A tail of the mRNA.
* **Option B:** This option is incorrect because the Shine-Dalgarno sequence is not involved in the regulation of gene expression through alternative splicing.
* **Option C:** This option is incorrect because the Shine-Dalgarno sequence is not a part of the ribosome itself, but rather a sequence in the mRNA that interacts with the ribosome.

**Clinical Pearl / High-Yield Fact**
The Shine-Dalgarno sequence is a critical element in the initiation of protein synthesis in bacteria, and its disruption can lead to the inhibition of translation. Understanding the role of this sequence is essential for the development of antibiotics that target bacterial protein synthesis.

**Correct Answer: C. Near the start codon (AUG)**