Correct option is (a) True
Best explanation: If u apply force on any link or joint the net force is distributed all over the structure ie sides and joints. This means all sides and joint experience force thus the force is distributed and this makes it more rigid and stable structure.
In case of all others shapes this is not present.
Example for square.—if u apply load on top link, joint the bottom link doesn’t experience any force. Hence the load is taken by two sides on which the square is standing. Similarly for pentagon, hexagon and all others.