Answer:
A. single nucleotide polymorphisms
What is a SNP (Single Nucleotide Polymorphism)?
The human genome has 3.2 billion bases, and a single nucleotide polymorphism (SNP) is a nucleotide substitution that may be found anywhere in those bases. By definition, an SNP is present in more than 1% of the "population" of people.
It turns out that defining exactly what an SNP is may be challenging and that the phrase is used relatively loosely in research. The higher 1% criterion can fail since SNP frequencies vary greatly depending on the human group you examine in (Caucasian, African, Asian, etc.). People frequently mention that these mutations are "benign," which is another characteristic that distinguishes SNPs. SNPs cannot be harmful since they tend to occur in relatively high numbers of people; otherwise, we would all be afflicted with sickness. Once more, this isn't always the case. Although frequent variations do not itself cause disease, it is generally known that they increase the risk of disease. There are now a number of SNPs with detectable biological consequences.