Which variable is likely to undergo the largest change in value resulting from a mutation that introduces a new allele into a population at a locus for which all individuals formerly had been fully homozygous?

Nucleotide variability represents a form of genetic variation that occur as a result of difference in nucleotide sequence of deoxy ribonucleic acid.

The locus is a region on the chromosome where genes are located. Average number of locus thus refers to total number of loci per total number of individuals in a population.

Geographic variability refers to difference in genetic traits across the various geographical distribution of a population.

Average heterozygosity is the percentage or proportion of heterozygous individuals for a trait within a population. It is a common measure of genetic variation in a population.

When a mutation occur within a population and this leads to the introduction of a new allele at a locus for which some individuals within the population are homozygous, it will directly affect the average heterozygosity of the population because more individuals will lose their homozygosity and become heterozygous.

The correct option is b.