But on that 1001st time, if the offspring comes out to be short, then what that means is it must be upper case t lowercase T. So if we do get a short offspring, we know definitely it's upper case. T lowercase T. But if we never actually get our short offspring, we can say that most likely our genotype of that initial plant following our test cross is T uppercase T uppercase T. So this is what we call a test cross. So a test cross is basically this experiment that we can conduct to basically help us determine what the genotype of that initial plant is, assuming we know what the phenotype is. So in this case, we have a phenotype that is tall. And so we have two possibilities. We conduct a test cross by testing, by crossing this tall phenotype with a plant whose phenotype and genotype we actually know.