Answer: 13,12,5
Step-by-step explanation:
According to the triangles inequality : The sum of any two sides of a triangle must be greater than the third.
since [tex]6+5 =11 \ngtr 15[/tex]
[tex]20+10=30\ngtr40\\\\ 16+2=18\ngtr19[/tex]
Only pipe lengths with measure 13,12,5 can form triangle as
13+12 >5
12+5>13
13+5>12
Hence, the correct option is 13,12,5.