It’s not clear how (A) involves subtracting out a baseline measurement in order to measure the level of change in something. Perhaps we could subtract the typical margin of voting from the unusually large margin observed in this case? But even if we interpret (A) in this way, the difference between the typical margin of voting and unusually large margin isn’t being associated with some circumstance — the author doesn’t try to attribute the difference in margin to some activity or other thing that might produce a greater margin of votes in that district.

This is the most analogous. There was an increase only during the summer — in other words, if you subtract the baseline level of sales throughout the year before the campaign from the level of sales throughout the year after the campaign, we see additional sales over the previous year only during the summer (just as we see increased oxygen use only in certain parts of the brain during a cognitive task). We interpret this as showing that the campaign affected only the summer shoppers (just as we interpret fMRIs as showing that mental activity is associated only with the parts of the brain showing an increase in oxygen use).

It’s not clear how (C) involves measurement of a change in something through the subtractive method. We’re not subtracting some baseline level of water use from the water use of agricultural customers. Rather, (C) involves a comparison of water use between agricultural customers and residential customers. In addition, the (C) doesn’t involve an interpretation of the difference in water use as being associated with something else. For example, (C) doesn’t say that the excess water use of agricultural customers must be due to something that affects only agricultural customers.

It’s not clear how (D) involves measurement of a change in something through the subtractive method. We’re not subtracting some baseline level of internet traffic from the amount of traffic in the evening. In addition, (D) doesn’t involve an interpretation of the difference in internet traffic as being associated with some specific circumstance. Rather, (D) makes a conclusion about “most” internet traffic during the evening; this isn’t a conclusion about the difference between evening internet traffic and baseline internet traffic.

It’s not clear how (E) involves measurement of a change in something through the subtractive method. We’re not subtracting the cheetah’s baseline level of speed from its top speed, for example.