im confused by this simple question, why is it supposed to be C?
I think its because its a test cross (ive not revised this - might need to if its tested if someone can clarify???) but this is from what I remember where you know one organism is homozygous recessive and you want to test the dominance of another organism (whether its homozygous or heterozygous)
which leaves option C
Yeah @SohamPaikaray is right, the main purpose of using the homozygous recessive in test cross, to ensure the how exactly dominant and recessive genes are transfer!! So which would lead the option C