Refer to the exhibit. 
A network technician is unable to ping from R1 to R2. What will help correct the problem?
A.
Ensure that the serial cable is correctly plugged in to the interfaces.
B.
Apply the clock rate 56000 configuration command to the serial0/1 interface of R1.
C.
Configure the serial0/1 interfaces on R1 and R2 with the no shutdown command.
D.
Change the address of the serial0/1 interface of R1 to 192.1.1.4.
E.
Change the subnet masks of both interfaces to 255.255.255.240.
Explanation: