Polymerase chain reaction (PCR) is useful for amplifying a small piece of DNA but is not a good technique for cloning genes because

A) DNA ligase cannot be used in PCRs.
B) PCRs do not generate palindromic sequences.
C) copies of DNA produced by PCRs lack the regulatory genes and proteins required to activate genes.
D) PCRs only generate primary transcripts that require excision of introns.
E) ribosomes are required to produce active genes.