Đáp án đúng: C
Giải chi tiết:\(\begin{array}{l}\overline {ab} + 589 = \overline {ab4} \\\overline {ab} {\kern 1pt} \, + \,589 = \overline {ab} \times 10 + 4\\\,\,\,\,\,\,\,\,\,\,589 = \overline {ab} \times 10 - \overline {ab} + 4\\\,\,\,\,\,\,\,\,\,\,589 = 9 \times \overline {ab} + 4\\\,9 \times \overline {ab} \,\,\,\,\,\,\, = 589 - 4\\\,9 \times \overline {ab} \,\,\,\,\,\,\, = 585\\\,\,\,\,\,\,\,\,\overline {ab} \,\,\,\,\,\,\, = 585:9\\\,\,\,\,\,\,\,\,\overline {ab} \,\,\,\,\,\,\, = 65.\end{array}\)
Chọn C.