Hi, SBieber,
Good analysis here. You are correct that "fewer large public gatherings" could be related to "avoiding public places." However, you are also correct that there is enough of a conceptual gap between these ideas to make answer choice (C) less helpful than answer choice (A). The argument is structured thus:
- Precautions (avoiding public places and washing hands) caused less influenza.
There was less influenza.
Conclusion: People must have taken the precautions (avoiding public places and washing hands).
The author concludes that because the effect occurred, the cause must have occurred too.
Answer choice (A), the correct answer, directly increases the likelihood that hand washing occurred. Since another effect of hand washing is less food borne illness, we have additional evidence that hand washing occurred.
Answer choice (C) does give some evidence that could corroborate avoiding public places, but the connection is more tenuous. Just because large gatherings occurred less frequently we do not know whether people avoided public places in general.
Here you have to make a judgment call: which answer provides more direct evidence that the purported causes did indeed occur. There is little doubt that (A) is the
better choice, even if you can make a case for (C).
I hope this helps!