执行PUSH AX指令的正确步骤是()

A.1.SP←SP-1,(SP)←AH

B.1.(SP)←AH,SP←SP-1 2.SP←SP-1,(SP)←AL 2.(SP)←AL,SP←SP-1

C.1.SP←SP+1,(SP)←AH

D.1.(SP)←AH,SP←SP+1 2.SP←SP+1,(SP)←AL 2.(SP)←AL,SP←SP+1