What Is the Purpose of Careful Primer Design Before PCR

What is the purpose of careful primer design before PCR?

A) Primers indicate the section of DNA that will be amplified and mark where DNA polymerase begins replication.
B) Primers allow for complementary nucleotides to be added to the new strand of DNA.
C) Primers are used to separate the original DNA strand to give polymerase a place to start replication.
D) Primers are the nucleotides that are used in a PCR reaction to form DNA strands.
E) Primers are enzymes that speed up the rate of a PCR reaction.