The answer is b i hope that helps
To start with, I've seen Samantha and Samandhi. And Samadhi Sutta, which interestingly discusses tranquillity and insight ( samatha and vipassana ).
There's another sutta which says that samatha and vipassana are paired qualities - samatha gets rid of passion, vipassana gets rid of delusion ( I'll see if I can find it ). Note that samatha is a quality, not a method.
There's three possible answers I found. The first one being that they worked in a bike shop, the second is that they were self taught, and the third is that there was this guy named Charlie Taylor who worked for them and he pretty much built the engine of their first planes
