favour vs. favor

[Lepi]

English Language Proficiency Tests, Advanced Level

ESL/EFL Test #30 "Letter Writing (2)", question 4

And now I come to a very important ......... I want to ask of you.

(a) favourite
(b) favour
(c) favourable
(d) favouring

English Language Proficiency Tests, Advanced Level

ESL/EFL Test #30 "Letter Writing (2)", answer 4

And now I come to a very important favour I want to ask of you.

Correct answer: (b) favour
_________________________

why not favor?

Lepi

[Mister Micawber]

.
Both spellings, the Br and the Am, are in favo(u)r.
.
_________________
Canadian-American native speaker
who teaches English for a living at Mister Micawber's
ESL cafe: Interview with Mister Micawber