"B" is the answer be careful question are very tricky. RPF methods in NSE guide says: Two ways to disable RFP.
1 Enable asymetric routing, which disables RPF checking system wide (but not at interface level is through the CLI command config system settings)
2 Disable RPF checkking at the interface level (the only way at the interface level in the CLI command).
A incorrect. If you enable asymetric routing, RPF not will be bypass because is disable.
B Correct. You have to disable the RPF check an the interface level, for the source.
C Is incorrect is for the source D is incorrect: Asymetric routing is not enable at interface level.
RPF checking can be disabled in the ways. If you enable asymmetric routing, it will disable RPF checking system wide. However this reduces the security of you network greatly. Features such us ANTIVIRUS, and IPS become non-effective.
So, if you need to disable RPF checking, you can do so at the interface level using the command:
config system interface
edit
set src-check [enable | disable]
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