The passage provides us with a bunch of evidence. The question asks us to draw a conclusion from that evidence. Inferences are unstated conclusions, statements that MUST be true from the evidence.

To start with the correct choice, E says that daytime streetlight regulations would probably do less to avert street crime in the continental United States than they do in the nations that have the regulations. We know this to be true because we are told that . . .

1) Regulations would be more successful in averting crime in nations farther from the equator AND
2) The only nations with regulations are farther from the equator than the US.

Put these two pieces of evidence together and it MUST be that the regulations wouldn't be as successful in the US.

You asked about Choice D. (Note: The writing of this choice is awkward, which might have confused you. You will not find this kind of writing on the actual test.) This choice compares the number of crimes in regulated nations to the number of crimes in the US. We can't conclude anything about this relationship, since the evidence is only about averting (preventing) crime. It might be that the regulated nations have much more crime, even though the regulations helped. Maybe the number of annual street crimes in a regulated nation dropped from 1 million to 1/2 million. That smaller number could be more than, the same as, or less than, the number of annual street crimes in the US. Who knows?

I'm available if you still have questions.