How to switch between E1 and T1 interfaces?

The MTU board can support 4 E1/T1 interfaces.

How to switch between E1 and T1 interfaces? Which statement is correct () (single choice)
A . You only need to select E1 or T1 in the "Parameter Configuration> Transmission Mode" in the "Quick Configuration> Configure Board" page on the U1900 Web management page, and the switch can be completed
B . The default is the E1 interface. To switch to T1, you need to remove the jumper cap inside the MTU board. Need to enter the Web management page to modify the configuration
C . The default is T1 interface, switch to E1, you need to remove the jumper cap inside the MTU board, and you need to enter the Web management page to modify the configuration
D . None of the above

Answer: B