What type of DNA does complementary DNA (cDNA) represent?

Complementary DNA (cDNA) is synthesized from a messenger RNA (mRNA) template through a process called reverse transcription. This means cDNA represents only the portions of RNA that have been transcribed into proteins, specifically the exons, as it does not include non-coding regions or introns that may be present in the original DNA.

The process of creating cDNA focuses on the mRNA, which has already undergone splicing to remove introns, resulting in only the coding sequences being retained. Therefore, the correct response accurately reflects that cDNA represents solely those segments of DNA that correspond to the mRNA that was transcribed, which includes the expressed genes without the non-coding sequences. This characteristic of cDNA makes it a valuable tool in molecular biology for studying gene expression.