Here. So if the short offspring actually appear, we know for sure that the genotype is uppercase t lowercase t. But if we conduct the experiment 1000 times and all the thousand times the offspring is always tall, then what that? Means is most likely the genotype of that offspring is actually uppercase T. Uppercase T. The reason I say most likely and not definitely because what can happen is, and this is very unlikely but it can still happen if I conduct the experiment 1000 times, it will appear tall. 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.