求助大家一个题目哈，这个题选 什么 Why will a switch never learn a broadcast a...

求助大家一个题目哈，这个题选 什么
Why will a switch never learn a broadcast address?
A,Broadcasts only use network layer addressing.
B,A broadcast frame is never forwarded by a switch.
- I8 L. p7 L2 F2 n3 q0 wC,A broadcast address will never be the source address of a frame.
+ m  {2 u" i1 Z: F+ l7 _D,Broadcast addresses use an incorrect format for the switching table.
) Q9 q0 L) a$ u' lE,Broadcast frames are never sent to switches.
5 t. X; p+ E4 n2 g

答案应是：
7 X2 V, V: b9 n: _1 kC,A broadcast address will never be the source address of a frame.

; s/ J" Y9 q: }7 u广播地址不可能用作源地址，因为在IP地址配置中，广播地址不能用作主机地址。