"A testcross involves an individual exhibiting the dominant phenotype but an unknown genotype being crossed with an individual that has a(n) genotype."

The correct answer is - h(omo)zygous recessive

Explanation:

When a cross between the organism with dominant phenotype, that can be heterozygous genotype or h(omo)zygous genotype, with a organism of h(omo)zygous recessive takes place, the cross known as test cross.

Test cross always exhibit an individual with the dominant phenotype. he aim of test cross is to find if the dominant individual is h(omo)zygous or heterozygous.

Thus, the correct answer is - h(omo)zygous recessive.

b is dominant over the allele for the white fur.