A clinical study is performed involving complex genetic traits such as hypertension, heart disease, and diabetes. The study makes use of naturally occurring variations in DNA sequences that are found in exons and introns and are frequent and stable. Which of the following genetic markers is being used in this study?
选项：

A:Proto-oncogenes
B:Robertsonian translocations
C:Single-nucleotide polymorphisms
D:Three–base pair frameshift deletions
E:Trinucleotide repeat mutations