Can't be 1970 while its 1980... so why we used what?

[Niveen (Palestine)]

English Grammar Tests, Elementary Level

ESL/EFL Test #93 "Why Questions", question 10

......... year did the first commercial aviation flight take place?

(a) When
(b) What
(c) Where
(d) Which

English Grammar Tests, Elementary Level

ESL/EFL Test #93 "Why Questions", answer 10

What year did the first commercial aviation flight take place?

Correct answer: (b) What

Your answer was: incorrect
Which year did the first commercial aviation flight take place?
_________________________

Hello,

In the "english teacher explanation" earlier, you distinguished between what and which as follows;
we use which, when the option is more than 1,2 or 3.
we use what for many options...
In this question the year is one option. can't be 1970 while its 1980... so why we used what?
Thanx

Niveen (Palestine)

[Yankee]

Hi Niveen

Even though there is only one correct answer, there is an unlimited number of possible options (years) to choose from in the question.

If the question had included a small number of specific possible choices, then you could have used "which". For example:

Which year did the first commercial aviation flight take place?
a. 1920
b. 1940
c. 1960

In the test question there were no specific choices for the year included; the options were unlimited (many) and "which" is not possible in that case.

Amy