The correct answer is: [C]: "subject and verb" .
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The two essential parts of [the sentence] are the "subject and the verb".
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NOTE: This is assumng that, among the 3 (THREE) answer choices given, the third option meant to be: "subject and verb" ; and that the word: "ad" ; was merely a spelling error—or "typographical error"—that was supposed to be: "and" . We futher confirm such an assumption based on the folllowing:
1) that the first 2 (TWO) answer choice are incorrect; 2) that: "subject and verb" ; would be a correct answer; 3) that there are only 3 (THREE) answer choices provided; 4) that the third answer choice: "subject ad {sic} verb" ; resembles "subject and verb" very closely; and 5) that there are no answer choices such as: "all of the above"; "none of the above"; or "the first and the third options are correct"
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