A three-factor cross in Salmonella typhimurium was performed using bacteriophage P22. The cross was between an arg-leu-his- recipient bacterium and bacteriophage P22, which was grown on an arg+leu+his+ strain. 1000 arg+ transductants were selected and tested on several selective media by replica printing. The following results were obtained:
Arg+ leu- his+ 300
Arg+ leu+ his+ 114
Arg+ leu+ his- 1
What is the order of the three markers?
What are the contransduction frequencies?