You went into Mendels Garden and stole pea plant with the dominant trait, purple flowers. How would you....?

....testcross it?

A. Mate it with a plant of unknown genotype

B. Mate it with a plant with white flowers

C. Mate it with both its parents

D. Mate it with a plant of unknown phenotype

E. Mate it with itself

You went into Mendels Garden and stole pea plant with the dominant trait, purple flowers. How would you....?
B.

A test cross is one where you cross an individual with a completely homozygous recessive genotype.
Reply:B, you are performing a testcross with a homozygous recessive plant. Then you can analyze the ratios and figure out what is going on.
Reply:B