Explanation

Creating a filter: as we're reading through the prompt, there seem to be an awful lot of modifying phrases set off by commas, but we may not see a definitive error.

Finding objective defects: as we compare answer choices, we can notice that a key choice is whether we start with the word "of," "also," or "also of." The answer to that question is determined by the prior phrase, near the beginning of the sentence, "inventor of both the Mills bomb..." To finish that off that "both," we need an "and," which we get before the underlined portion. "Also" is redundant. And the word "of" is not permitted, because the first "of" comes before "both." That leaves only one possibility: the correct answer is (E).