verb agreement

[Bobbie]

Mary reported that preparation of these documents (was, were) in process.

I think the very is "was" because it refers to preparation. Is this correct?

[MikeNewYork]

Mary reported that preparation of these documents (was, were) in process.

I think the very is "was" because it refers to preparation. Is this correct?

Absolutely correct! :D

[Tdol]

This is a quite a common mistake where the subject has both singular and plural elements in it and people make the verb agree with the noun closest to it.