Which of the Following Make(s) Amplification of a DNA Fragment

Multiple Choice

Which of the following make(s) amplification of a DNA fragment by means of the polymerase chain reaction possible?

A) Complementary single-stranded nucleic acid sequences can come together to form a duplex molecule.
B) Duplex nucleic acid molecules can be separated by size by means of electrophoresis.
C) A restriction enzyme cleaves duplex DNA molecules only at the positions of certain short sequences constituting the enzyme's restrictions site.
D) DNA polymerase elongates a growing DNA strand by the addition of successive deoxynuclotides to the 3' end.
E) DNA ligase is an enzyme that can join the ends of single-stranded DNA molecules.