IMO: C

IMO D.

Before comparing the effect of 2 entities, the quantities should be taken into consideration.

Here we are comparing the number of conviction cases of public defendents vs private defendants.

Hence we need to make sure that the quantites are balanced before comparison.

Only D addresses this point.

Hi,

this is another causal or explain the phenomenon argument.

Phenomenon: criminals who commit lucrative crimes are more successful at avoiding conviction than are street criminals.

The author's explanation: rich white-collar crime commiting defendants can afford better lawyers.

This argument can be weakened by pointing to an alternative explanation: for example, maybe the reason street criminals are more likely to be successfully prosecuted is that they are more likely to actually be guitly of the crimes with which they are charged. Conversely, this argument can be strengthened by ruling out such an explanation--that's exactly what the correct answer, choice D, does. (If you deny choice D, you will see that the argument is weakened; hence, choice D strengthens).

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Takeaway:
--recognize causal or explain the phenomenon arguments, as they often show up in stn/wkn questions. Such arguments can be weakened by introducing an alternative explanation and strengthened by removing an alternative explanation.

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Choices A, B and E actually weaken the argument.
Choice C is about NUMBER while the argument was about conviction RATE. Thus, choice C is irrelevant.