问题：

[单选]

When you enable port security on an interface that is also configured with a voice VLAN， 
what is the maximum number of secure MAC addresses that should be set on the port？（）

A . No more than one secure MAC address should be set.
B . The default will be set.
C . The IP phone should use a dedicated port， therefore only one MAC address is needed per port.
D . No value is needed if the switchport priority extend command is configured. 
E . No more than two secure MAC addresses should be set.