c = nλ,

1/λ is n/c. Going by this formula, n is frequency and c is speed of sound in vacuum that is 3X10^8 m.

Can we define wavenumber as number of waves produced in a distance of 3X10^8 metre?

In my exam, i had this question

Wave number is defined as number of waves

1)produced in one second

2)produced in a distance of 3*10^8 metre

3)produced in a distance of λ metre

4)produced in a distance of 1 metre.

I think both 2) and 4) are correct. Am i right?