Which of the following sets of lengths could not be the side lengths of a triangle?
3 meters, 5 meters, 7 meters
1 yard, 1.25 yards, 1.5 yards
5 inches, 10.5 inches, 17 inches
15 millimeters, 18 millimeters, 30 millimeters

To find out if the three side lengths can create a triangle, the three smaller lengths must be greater than the longer length.







So this can create a triangle.







So this can create a triangle.







So this cannot create a triangle.







So this can create a triangle.

Therefore, your answer is Option C.