以下选项中能表示合法常量的是

A．switch(x%2)
ease 0: a++; break;
ease 1: b++; break;
default: a++; b++;

B．switch((int)x/2.0)
case 0: a++; break;
case 1: b++; break;
default: a++; b++;

C．switch((int)x%2)
ease 0: a++; break;
ease 1: b++; break;
default: a++; b++;

D．switch((int)(x)%2)
case 0.0: a++; break;
ease 1.0: b++; break;
default: a++; b++;