💡 Detailed Explanation
The task is to rearrange the options to form a coherent sentence. The correct order is "彼の無責任な発言は、被災者の方々に対して 失礼(1) 極まりない(2) もの(3) だ(4)". Therefore, "もの" goes in the ★ position. The grammar pattern "〜極まりない (kiwamarinai)" means "extremely..." or "nothing could be more..." and is used to strongly emphasize a negative state. It attaches directly to nouns or the stems of na-adjectives.