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