During RNA splicing, which one of the following is removed?

Options

A. Primary transcripts
B. Exons
C. Introns
D. Both (2) and (3)

Answer

### Step-by-Step Solution:

1. **Understanding RNA Splicing**: RNA splicing is a process that occurs during the maturation of precursor mRNA (hnRNA) into mature mRNA. This process is essential for the proper expression of genes.

2. **Identifying Components of hnRNA**: hnRNA contains both exons and introns. Exons are the coding sequences that will be expressed as proteins, while introns are non-coding sequences that do not contribute to the final protein product.

3. **The Process of Splicing**: During RNA splicing, the introns are removed from the hnRNA. This is a crucial step because introns do not code for proteins and must be eliminated to produce a functional mRNA.

4. **Joining of Exons**: After the introns are removed, the exons are joined together to form the mature mRNA. This mature mRNA is then ready for translation into a protein.

5. **Conclusion**: Therefore, the component that is removed during RNA splicing is the introns.

### Final Answer:
**Introns are removed during RNA splicing.**

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