So maybe if the second choice had still been "T", I would have picked another response. I am puzzled how I hadn't seen the default length of 30 before, yet the great majority of over 800 respondents to this QOD got it right. Oh, well. One more poke in the ribs that I've still got lots to learn.
Of course I agree with others that it would be better not to depend on a default value, especially one as seemingly capricious as this one. Come to think of it, 30 makes some sense -- 30 characters and two more to hold the "real" length make 32, a power of two (just a guess).