Use the Following Information to Answer the Question

Multiple Choice

Use the following information to answer the question.
A plantlike organism on the planet Pandora can have three recessive genetic traits: bluish leaves, due to an allele (a) of gene A; a feathered stem, due to an allele (b) of gene B; and hollow roots due to an allele (c) of gene C. The three genes are linked and recombine.
A geneticist performed a testcross with an organism that had been found to be heterozygous for the three recessive traits, and she was able to identify progeny of the following phenotypic distribution (+ = wild type) :

What is the greatest benefit of having used a testcross for this experiment?

A) The homozygous recessive parents are obvious to the naked eye.
B) The homozygous parents are the only ones whose crossovers make a difference.
C) The phenotypes of the progeny reveal the allelic content of the gamete from the heterozygous parent.
D) All of the progeny will be heterozygous.