A:BamHI和EcoRI;末端互补序列—AATT—
B:BamHI和HindⅢ;末端互补序列—GATC—
C: EcoRI和HindⅢ;末端互补序列—AATT—
D:BamHI和BglII;末端互补序列—GATC—
“种姓制度”实行于( )