http://classic.7sage.com/lsat_explanations/lsat-19-section-2-question-07/

I'm a little confused by this one...

Could anyone explain why Answer Choice B is correct?

http://classic.7sage.com/lsat_explanations/lsat-20-section-1-question-05/

After reading the answers, I think I can see how this one justifies the argument but still a little unsure about how the answer was found.

What were the steps?