This concludes there’s a causal relationship (money supply being constant causes stable interest rates) based on premises that show the absence of the cause is associated with less of the effect (when money supply isn’t constant, interest rates are not stable) and that the presence of the cause is associated with more of the effect (when money supply is constant, interest rates are stable).

This doesn’t have a premise showing that the presence of the alleged cause is associated with the effect.

This doesn’t involve premises about the presence or absence of the alleged cause.

The conclusion doesn’t assert that there’s a particular causal relationship. Rather, it asserts that there are some other causal factors in voting behavior besides records of political achievement. This conclusion doesn’t single out a particular cause, so it doesn’t allow for a parallel structure.

This doesn’t involve premises about the presence or absence of the alleged cause. The alleged cause is having “many other activities to divert [adults from reading.” In order to be parallel, we want a premise about what happens when there are not many other activities to divert adults from reading, and a premise about what happens if there are many activities to divert adults from reading. But the premises in (E) don’t concern the number of activities; they concern what happens when people spend more or less time on other activities. The amount of time spent on other activities is not the same as the number of activities that are available to divert one’s attention.