The cultured E. coli system was infected by two types of bacteriophages. One type is a-b-, another is a+b+. Then the lysate was sampled and smeared on medium. The data of the bacteriophage growth by counting plaques is as follows: a+b+=4750, a+b-=370, a-b+=330, a-b-=4550. How much is the recombination rate between a and b ______
A. 70%
B. 12.8%
C. 7%
D. 15%
In a strain of fruit fly, after several times of artificial hybridizations, the map distances of the given loci is A-B=10 m.u., A-C=20 m.u., A-D=25 m.u., B-C=30 m.u., B-D=15 m.u., If the genetic map is drawn according to these humbers, the correct locus order should be ______.
A. DCBA
B. DBAC
CADB
D. ACDB