Who sez it's Usn's got it backerds?

Wh...why, I thought everyone knew that! Some things are just axiomatic! Don't waste your intell..., um,

(a) -ect
(b) -igence
(c) Neither of the above
(d{i}) Both of the above if one drives the other
(e{ii}) Both of the above if one drives the other, but the other way around
(e) Both of the above if they are cognates
(f) Both of the above if you feel like it ...

... worrying yore purty li'l haid about it, Faldo. This, too, shall farce.