the thing it was advisable

[navi tasan]

Which of these sentences are correct:
1-"The thing it was advisable to do was call John."
2-"The thing which it was advisable to do was call John."
3-"The thing it was advisable to do was calling John."
4-"The thing which was advisable to do was call John."

[Red5]

Which of these sentences are correct:
1-"The thing it was advisable to do was call John."
2-"The thing which it was advisable to do was call John."
3-"The thing it was advisable to do was calling John."
4-"The thing which was advisable to do was call John."

The best of those that you've offered is #4. I wouldn't use any of them myself.

I'd be more likely to say something like "The advisable thing to do was call John.".

The best of all would be "It was advisable to call John".

[Tdol]

What Red said.

[MikeNewYork]

What TDOL said.