Difference between 'during', 'in' and 'of'

Question

Incorrect: Whereas it had been possible to at least consider the draft proposal of the directors, none of the two options of the final bargaining round were acceptable because of the bulk of the finance stipulated in the fine print depended on output.

Correct: Whereas it had been possible to at least consider the draft proposal of the directors, neither of the two options during the final bargaining round was acceptable because the bulk of the finance stipulated in the fine print depended on output.

The above-mentioned question is from GMAT. This question is based on subject-verb related. But my question is related to preposition, that is,

1. Why did they use during instead of of?

2. Is it fine if I use in instead of of?. If so, what is the difference I am making here?

Answer 1

I don't think of is strictly wrong in this sentence, but its meaning is vague. Do the options "belong to" the round? Possibly, but it's more accurate to say that the options were proposed during the final round. As you suggest, in is also a better choice than of. One of the definitions of in is this: "expressing a period of time during which an event takes place or a situation remains the case." So it's similar to during in this case.