When there is NO change in the allele frequency, this is called genetic

Either genetic frequency or genetic drift . genetic drift takes place when the occurrence of variant forms of a gene, called alleles, increases and decreases by chance over time; genetic frequency is an allele that’s defined as the total number of copies of that allele in the population divided by the total number of copies of all alleles of the gene. HOPE THIS HELPS!!!

Cbecause it is the only one describing a habitat