In a fruit fly (Drosophila melanogaster)family, alleles aer, brt and cts are all homozygous in recessive somatic cells. The 3 loci of aer. brt and cts are linked in order. Crossing the female flies of this family with male wild-type fruit flies, and make F₁ heterozygous individuals intercross, the F₂ are produced as follows:
+ + + 4365
aer brt cts 1168
aer brt + 278
+ + cts 269
aer + + 150
+ brt cts 141
aer + cts 16
+ brt + 13
(1)Please analyse and calculate the recombination frequency between aer and brt and that between brt and cts.
(2)How much is the coefficient of interference

A．recombination frequency may be directly obtained according to phenotypic ratios, but crossover value cannot be directly obtained according to phenotypic ratios
B．crossover value may be replaced by recombination frequency or chiasm frequency you get from the observation under microscope when genetic distance is considerably short
C．crossover value may be replaced by recombination frequency when genetic distance is as a medium value, not too long and not too short
D．recombination frequency will be very different from crossover value when there is a third locus in between the two loci you analysed

A．Aa
B．AA
C．aa
D．unable to be inferred