Refer to the exhibit. You are setting up a 2-gigabit EtherChannel. Following IEEE standards， the exhibit shows your configuration in a local switch1. However， EtherChannel is not coming up. Which one of these statements could be a possible reason？（）

• A、 EtherChannel is only available in Cisco equipment. 
• B、 The customer side is supposed to be running PAgP, which is a Cisco standard. 
• C、 PAgP is not an IEEE standard. VRRP should be used. 
• D、 The configuration on switch1 needs to be modified to use LACP.