There are two primary considerations here: the placement of the word "unusual" or "unusually" and the parallel structure of the sentence. Because the sentence is built on a comparison (Claudius compared to his predecessors), it makes the most sense that it is his involvement in the day-to-day workings that is unusual, as seen in choices (B), (D), and (E).

Among those three choices, (B) and (D) move the phrase "day-to-day" to modify "judicial system," which is unidiomatic, leaving only choice (E). Consider also the parallel structure. "Taking" and "settling" are parallel to each other, and both are further elaborations of Claudius's unusual level of interest. Choice (E) is correct.