Answer
B., C.
Work Step by Step
This question in the book is not well put. The book says that the answer is C., which is true since our cells need DNA ligase for copying chromosomes but PCR does not involve sticking pieces of DNA together covalently using ligase. However, our DNA Polymerase is not stable at high temperatures needed for DNA denaturation during PCR (see p. 332) while the polymerase used for PCR is stable at those high temperatures.
