Question

... better trained we might make a large profit a. was our staff b. had been our staff c. were our staff. D. having been our staff​

Answer 1

Were our staff  better  trained,  we  might  make a larger profit. (= If our staff were better trained.-Условное 2 типа

Ответ:  c. were our staff

Answer 2

The correct answer is: c. were our staff.

The sentence is in the subjunctive mood, indicating a hypothetical or unreal condition. In this case, we are discussing a hypothetical scenario related to the staff being better trained and the potential for making a large profit. When using the subjunctive mood to express a hypothetical condition, we use "were" (not "was") for all persons.

So, the correct construction is: "were our staff."