In the triangle sum of two sides should be more than third side.
6+11=17
3d side is less than 17.
3d side should be more than difference of 2 other sides.
11-6=5
3d side should be more than 5.
Perimeter should be more than (11+6+5=22), but less than (11+6+17=34).
22 < Perimeter < 34
We have only one answer
22<30< 34
Answer: D.30.