in drosophila, two genes p and m are completely linked. if a double heterozygote : p m / p m is test crossed, then question 6 options: all progeny will be p m / p m about 50% of the progeny will be p m / p m and about 50% will be p m/ p m none of the above all progeny will be p m / p m all progeny will be p m / p m