Which among the following is a test cross ?

Tt × tt

The correct answer is option (3) -Tt × tt

                                           Diagrammatic representation of a test cross

Mendel crossed the tall plant from F2 with a dwarf plant. This he called a test cross. In a typical test cross an organism showing a dominant phenotype (and whose genotype is to be determined) is crossed with the recessive parent instead of self-crossing. The progenies of such a cross can easily be analysed to predict the genotype of the test organism.