执行MOV AX，WDAT指令时，要使AX寄存器中内容为3412H，不能采用下列哪种数据段定义

A．DSEG SEGMENT
WDAT EQU WORD PTR BDAT
BDAT DB 12H，34H
DSEG ENDS
B．DSEG SEGMENT
BDAT DB 12H，34H
WDAT = WORD PTR BDAT
DSEG ENDS
C．DSEG SEGMENT
WDAT FQU THIS WORD
BDAT DB 12H，34H
DSEG ENDS
D．DSEGSEGMENT
BDAT DB 12H，34H
WDAT LABEL WORD
DSEG ENDS