A Plantlike Organism on the Planet Pandora Can Have Three

Multiple Choice

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 did a testcross with an organism that had been found to be heterozygous for the three recessive traits and was able to identify progeny of the phenotypic distribution (+ = wild type) shown in the figure below.
If recombination frequency is equal to distance in map units,what is the approximate distance between genes A and B?

A) 1.5 map units
B) 3 map units
C) 6 map units
D) 15 map units