We know that The triangle inequality<span> states that for any </span>triangle, t<span>he sum of the lengths of any two sides of a </span>triangle<span> is greater than the length of the third side </span>so case <span>A. 81 mm, 7 mm, 6 mm 6+7 is not > 81
case </span><span>B. 81 mm, 7 mm, 72 mm 72+7 is not > 81
case </span><span>C. 81 mm, 7 mm, 88 mm 81+7 is not > 88
case </span><span>D. 81 mm, 7 mm, 77 mm 81+7 is > 77------> ok 77+7 is > 81-----> ok 81+77 is > 7-----> is ok
the answer is the option </span>D. 81 mm, 7 mm, 77 mm