Final answer:
A library of cloned sequences representing the expressed genes of an organism is known as a E) cDNA library, which is created by reverse transcribing mRNA into cDNA and then cloning it for research purposes.
Step-by-step explanation:
A library of cloned sequences representing the expressed genes of an organism is known as a cDNA library. This type of library is generated by reverse transcribing mRNA, which reflects all of the genes expressed in a given cell type at a moment in time. Only the sequences that are actually translated into proteins are included in a cDNA library, unlike a genomic library that represents all possible fragments of an organism's genome. Constructing a cDNA library involves isolating cellular mRNA and converting it into cDNA using reverse transcriptase. The cDNA molecules are then cloned into plasmids or bacteriophage, allowing researchers to analyzethe DNA encoding polypeptides and study different aspects of gene expression.