Final answer:
Option A) tt is the homozygous recessive allele because it consists of two identical recessive alleles 't', which is required for a homozygous recessive genotype.
Step-by-step explanation:
The question asks which of the following is a homozygous recessive allele: A) tt B) GG C) Bb D) Ww. To determine a homozygous recessive genotype, we need to find an option that has two identical alleles (which means 'homozygous') and also represents a recessive trait. A recessive trait will be observed in individuals that are homozygous (option c from the reference information) for that trait since both alleles need to be recessive for the trait to be expressed when a dominant allele is not present to mask the recessive one.
An individual or organism is considered heterozygous when it has two different alleles for a specific gene, such as Tt. On the other hand, an individual is considered homozygous when it has two of the same alleles, for example, TT for homozygous dominant or tt for homozygous recessive. Based on this understanding, option A) tt is a homozygous recessive allele since both alleles 't' are the same and recessive.