对于IPv6协议，240e:0186:0014:0000:0000:000c:0000:2/126表示的掩码地址是（          ）

A、ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffc0
B、ffff:ffff:ffff:ffff:ffff:ffff:ffff:ff00
C、ffff:ffff:ffff:ffff:ffff:ffff:ffff:fff0
D、ffff:ffff:ffff:ffff:ffff:ffff:ffff:fffc