单项选择题

与y=(x>0 1:x<0 -1:0);的功能相同的if语句是

A.if(x>0)y=1   else if(x<0)y=-1;   else y=O;
B.if(  if(x>0)y=1;  else if(x<0)y=-1;
C.y=-1;  if(  if(x>0)y=1;  else if(x==0)y=0;  else y=-1;
D.y=0;  if(x>=0)  if(x>0)y=1;  else y=-1;