Apart from the enzyme, what 3 DNA molecules are required (give the technical names by which they are called)? What must be true about the sequences of these molecules? Note that dNTPs are individual nucleotides, not DNA molecules.

1. Single strand DNA (target DNA)

2. 2 Primers ( Forward and reverse primers)

Explanation:

Polymerase chain reaction or PCR technique Is based on the DNA replication process that is it requires the Taq polymerase, the primers, and the target DNA.

The DNA sample is denatured in the first step which opens the strands and forms two single strands.

To these two strands, the primers which are the short nucleotide sequence that provides the 3'end for Taq polymerase are attached on both the strands.  The forward primer binds to the start codon at 3' end and reverse primer binds to the stop codon.  

Thus, these are the 3 sequences which are required in the PCR.

substitution is the answer in this case

looks like the answer is     c     to me!