This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of nucleic acids, Subject name: Biochemistry
A segment of a eukaryotic gene that is not represented in the mature mRNA, known as 
Select and explain. 
A. Intron, B. Exon, C. Plasmid, D. TATA box
A: Intron
Answer: A: Intron 
Explanation: The primary transcript are very long, they have molecular weights more than 10^7The primary transcript contains coding regions -extrons and non-coding regions -intronsThe introns sequence are cleaved and the exons are spliced to form mature mRNA moleculeRef: DM Vasudevan, 7th edition, page no: 591