Identify the test cross here.

Here, the test cross is Tt × tt.
In a test cross, the individual in question is bred with another individual that is homozygous for the recessive trait, and the offspring of the test cross is examined. Here, ‘Tt’ is heterozygous dominant and the other parent ‘tt’ is homozygous recessive.
By performing a test cross, one can determine whether the individual is heterozygous or homozygous dominant.