Is it 'by' or some other preposition in- 'The internet is also a platform by which online tutoring is made possible'

Question

Is it 'by' or 'for' or 'through' or 'on' the preposition in the following-

'The internet is also a platform by which online tutoring is made possible'

Answer 1

Several prepositions would be acceptable here, including by, on, via and through.

But for doesn't work because the sense here is of the means that makes online tutoring possible rather than its purpose.