A Plant-Like Organism on the Planet Pandora Can Have Three

Multiple Choice

A plant-like 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) :
$$\begin{array} { | l | l | l | l | l | } \hline \text { Phenotypes } & \text { Leaves } & \text { Stems } & \text { Roots } & \text { Number } \\\hline 1 & a & + & + & 14 \\\hline 2 & a & + & c & 0 \\\hline 3 & a &b &+ & 32 \\\hline 4 & a &b& c & 440 \\\hline 5 & + &b& + & 0 \\\hline 6 & + &b& c & 16 \\\hline 7 & + & + & c & 28 \\\hline 8 & + & + & + & 470 \\\hline & & & \text { Total } & 1000 \\\hline\end{array}$$
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If recombination frequency is equal to distance in map units, what is the approximate distance between genes A and B?

A) 3 map units
B) 6 map units
C) 15 map units
D) 30 map units