The right answer is corrupt because you're looking for a synonym of ignoble.
You should look at web sources that have recently been updated because a lot of times new information is present that could change the original point/evidence. This could discredit the source. You also should do this because the newer the information, the more credible it is in the time (older information could easily be outdated).
The Vietcong set up checkpoints around the nation, so that would've definitely been a literal and figurative roadblock to any refugees. Hope this helped.
It looks like 2) "it" would need to be changed.
