You’re given two side lengths of 3 centimeters and 5 centimeters. which measurement can you use for the length of the third side to construct a valid triangle?
8 centimeters
6 centimeters
4 centimeters
10 centimeters
2 centimeters

Since the third (and largest) side must be less than the sum of the two smaller sides, the answer has to be less than 3+5=8. This leaves us with 6, 4, and 2. However, 2 cannot work because it would be the middle side length, and 3+2 would be 5, which is impossible.