A.The VLAN to instance mapping is a normal 16-byte field in the MST BPDU.
	B.The VLAN to instance mapping is a normal 12-byte field in the MST BPDU.
	C.The VLAN to instance mapping is a 16-byte MD5 signature field in the MST BPDU.
	D.The VLAN to instance mapping is a 12-byte MD5 signature field in the MST BPDU.
 
                            