He used riddling to talk to Smaug I think because he wanted to stall and waste time as he figured out a plan. He also used riddles to talk to Golem who he clearly was trying to stall to save himself as Golem wanted to kill and eat Bilbo. So it is a reoccurring theme of Bilbo and it makes sense.
The similarity that Twan and Baker share, regardless of the fact they lived at different times, is C) both experience events that test their self-assurance.
