Firstly, the higher rates per capita may be triggered by two aspects: either the higher numerator, which is the amount of used internet, or the lower denominator, which is the population. Hence, either of these two aspects could trigger the discrepancy described in the argument.
A.
This seems complementary to the actual argument, but this wouldn’t account for the ratio being higher: that is, if everyone uses the internet for work, we would expect the per capita usage to be similar across regions, but not higher for the censored countries.
B.
Again, while there are some services that allow the users to overcome censorship, this doesn’t explain why the per capita ratio becomes higher for such countries. Equal or non-different from the rest of the world – yes; but higher – not really.
C.
While vague, this is the only point that provides us with at least some justification for cross-regional differences. That is, there’s a methodology discrepancy which can significantly distort the values across countries – so in theory it could explain the different per capita usage. This seems like the right answer.
D.
This is not explanatory because higher populations would actually lead to lower per capita ratio, which is the opposite of our case.
E.
Once again, we have the argument that applies to both censored and non-censored countries, so wouldn’t explain the discrepancy between them.
Therefore, IMO the correct response is C.
Posted from my mobile device