What is complimentary DNA (cDNA) derived from?

Complementary DNA (cDNA) is synthesized from messenger RNA (mRNA) through a process called reverse transcription. This process specifically targets the exonic regions of mRNA, which are the coding segments that contribute to the formation of proteins. During the transcription process, introns, which are non-coding regions of DNA, are spliced out, and only the exons are joined together to form mature mRNA.

When cDNA is synthesized from mRNA, it contains only these exons, reflecting the sequence that ultimately gets translated into a protein. Therefore, cDNA serves as a valuable tool for studying gene expression, as it allows researchers to analyze the coding sequences that are actively expressed in cells at a given time. This focus on exons is what makes this answer the correct choice in the context of the question regarding the origin of cDNA.