You are trying to produce cDNA starting from mRNA in skeletal muscle cells. You add the following components to a tube and let the reaction proceed: skeletal muscle mRNA, free nucleotides, and DNA polymerase. After inspecting the products of the reaction, you do not find any cDNA molecules at all. What is the most likely explanation for this result?
◦ You used mRNA instead of genomic DNA as the source material.
◦ You used DNA polymerase instead of reverse transcriptase.
◦ You forgot to add a radiolabeled nucleic acid probe to the tube.
◦ cDNA can only be made from skin cell mRNA molecules.