💡 Detailed Explanation
The man is considering turning down the promotion because, as a manager, he would have to step away from the hands-on, creative process of product development ('自ら手を動かして設計したり、試行錯誤したりする現場の実務からは離れざるを得ない'). He states that his passion lies in this creative process ('僕のやりがいは、アイデアを形にしていく、その創造的なプロセスそのものにあるんだ'), and he is reluctant to lose that connection. Option 1 is incorrect as he says he's confident. Option 2 is incorrect as he says he's used to long hours. Option 3 is close, but the core reason is not a dislike of management itself, but the loss of his beloved hands-on work.