Which one of the following statements regarding single-stranded conformational polymorphism (SSCP) analysis is incorrect?

a.​SSCP is used to assess a specimen for the presence of unknown variants in a nucleic acid sequence.
b.​SSCP distinguishes altered gene sequences by detecting a change in the three-dimensional structure of a piece of single-stranded DNA.
c.​SSCP is a polyacrylamide gel electrophoresis procedure.
d.​In SSCP, separation of a PCR product is performed with a gel that includes a concentration gradient of denaturants