Thousands of snps across the genome were analyzed in pooled dna samples from humans who had been sorted into groups according to their age. for the vast majority of these sites, there was no change in the relative frequencies of different variants as these humans aged. sometimes, albeit rarely, a particular variant at one position was found to decrease in frequency progressively for people over 50 years old. which of the possible explanations seems most likely?
a) those people born more than 50 years ago came from a population that tended to lack the disappearing snp variant.
b) the nucleotide in that snp at that position is unstable, and mutates with age.
c) the snp variant alters an important gene product in a way that shortens the human life-span, so these people are no longer part of the statistics used to calculate frequencies in the aging populations, or is linked to a neighboring allele that has this effect.
e) dna repair processes are able to recognize the differences and repair them, and the older the people the more likely this is to happen.
f) none of the above.