gplaya123, I'm so thrilled to see you flexing your RC muscles by working through explanations for wrong answers! It's some of the very best possible training you can do!
However, you need to be extra careful to fully support your analysis with the passage! Your assessment of the tests used in the past, and their problems, is spot on.
But what, exactly, is this 'better test'? Line 65 tells us that it is a "comparison of each of these economic indicators with the frequency of the movement-initiated events reported in the press."
What exactly are we comparing?
"these economic indicators" - what is this referring to? What economic indicators? The ones just previously mentioned:
1) steady rise in median black family income
2) stability of the conomic position of black vis-a-vis white Americans and
3) unemployment data
VS"the frequency of movement-initiated events reported in the press" - how often movement events show up in the news.
The passage indicates that none of the economic indicators "correlates significantly with the pace of reports about movement activity."
It is critical to realize that we are
not comparing how often the economic indicators are mentioned in the press! We are comparing the economic data (the straight math!) to the news-frequency of movement events.
(A) undermines this 'better test' by suggesting that not all movement activity gets reported. That would mean that the new-frequency of movement events would be an inherently untrustworthy number, skewering the 'better test' comparison.
(B) talks about the press coverage of the economic indicators. We do not care about that! The 'better test' compares the economic indicators as mathematical data, it does not depend on how often they were mentioned in the news.
Does that help clear up what precisely the 'better test' is, and why (B) is not a weakener here?