On a newly installed AIX V4 machine, which of the following default values applies to the ipforwarding network option?（）

• A、 The ipforwarding is off by default. 
• B、 The ipforwarding is set on by default. 
• C、 The value is dynamically determined at boot time by DHCP. 
• D、 The value is equal to the setting of the directed_broadcast runtime attribute.