Answer: D (21 m, 6 m, 10m)
Step-by-step explanation:
The sum of 2 sides of a triangle should always be greater then the third side of the triangle.
On answer D:
21 and 6 makes 27 and 27 > 10
10 and 21 makes 31 and 31 > 6
but 6 and 10 makes 16 and 16 < 21
