Cross the long-finned fish with short-finned fish; if the offspring are all long-finned, the long-finned parent is homozygous.
Imagine that long fins in zebrafish is a dominant trait. A breeder wants to set up a breeding program beginning with homozygous dominant long-finned fish. If she obtains a handful of the rare long-finned fish, how can she tell which if any of these are homozygous for the trait?
True or False

True

Explanation:

In order for the breeder to know if the long fined fish are homozygous. He will have to cross the Long finned with short finned

If the long finned was homozygous, all the F1 will be long finned zebrafish. This is because long fin is dominant over short fin.

However, if the long finned zebrafish were heterozygous. The cross will produce two long finned and two short finned zebra fish.

if you listed your answers right then i believe your answer is b.