Answer:
All answers could be B, C and D
Explanation:
According to the triangle inequality theorem, the combined length of two sides of a triangle cannot exceed the length of the third side. so:
13+8=21
Which means the sides that are less are A, B, C and D
Now A is smaller terms, if we try to use this to apply to a different way:
8+5=13
13=13
This means that the combined terms are NOT as small as the third side, and therefore this length cannot work. Therefore, the only ones left are lengths B, C and D