The correct answer is C. The pipe is use for filter the output

C pipe character used for filter

C is correct for filter outputs

The correct answer is C. Explanation: The vertical bar | character in the Junos OS is known as a pipe, and it is used to filter or modify the output of a command. In the context of the show | compare rollback 49 command, the pipe filters the output of the show command by sending it to the compare rollback 49 command. The compare rollback 49 command then compares the current configuration with the rollback configuration number 49. Option A is incorrect because the pipe character in the Junos OS is not used to represent an "either or" statement. Option B is incorrect because the greater than > character is used to redirect output from a command line to a file, not the pipe character. Option D is incorrect because the pipe character does not change the command from an operational command to a configuration mode command. Rather, it modifies the output of the command.

correct, it's for filter

Ref: Filtering Operational Command Output | Junos OS | Juniper Networks “Filtering Operational Command Output … The pipe | symbol lets you (the network administrator) filter the command output in both operational and configuration modes. …”

C is correct answer, Because | filter is not change, It just only view output configuration when rollback.

C is correct (filtering)

must be D root# show | compare [edit interfaces ge-0/0/4] + description test;