The correct option is C Unpaired bases
DNA end or sticky end refers to the properties of the end of a molecule of DNA or a recombinant DNA molecule. The sticky ends form base pairs. Any two complementary cohesive ends can anneal, even those from two different organisms. This bondage is temporary however, and DNA ligase will eventually form a covalent bond between the sugar-phosphate residue of adjacent nucleotides to join the two molecules together.