This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Which test uses oligomer with single base pair substitution as a primer - 
Select and explain. 
A. PCR, B. RFLP, C. Error coded mutation analysis with PCR, D. Site directed mutagenesis
D: Site directed mutagenesis
Answer: D: Site directed mutagenesis 
Explanation: Site-directed mutagenesis or oligonucleotide-directed mutagenesis uses oligomer with single base pair substitution as a primer to create a specific DNA sequence change (in gene), thus producing modified proteins with a change in primary structure.