Question

in addition to DNA polymerase and primers, the polymerase chain reaction also requires, A. a large amount of DNA, B. restriction enzymes, C. a supply of the four DNA nucleotides, D. complementary sequences of DNA

Answer 1

Let's think about what PCR does. It basically generates lots of copies of a DNA sequence. Now let's see what we've got; DNA polymerase which is an enzyme and primers which basically tell the polymerase where to start creating new DNA.
Now let's go through the answers:
A. A large amount of DNA - No, why would we need this? The point is to make copies of DNA.
B. Restriction enzymes - Nope, restriction enzymes cut DNA.
C. A supply of the four DNA nucleotides - There's the answer! You need a supply of the nucleotides in order to build copies of DNA.
D. Complementary sequences of DNA - the PCR will generate it's own complement to the DNA template.

Answer 2

Really nice answer!