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.&e