狒狒逻辑45

上邪

adequate solution means a feasible way, one of all feasible ways...
required solution means the only way ...
充分必要的问题

Commissioner: Budget forecasters project a revenue shortfall of a billion dollars in the coming fiscal year. Since there is no feasible way to increase the available funds, our only choice is to decrease expenditures.
our only feasible way is to

this promise told us to decrease expenditures is the only feasible way we have to do...but it is not the required way
there can be other choices ...

however
The plan before you outlines feasible cuts that would yield savings of a billion dollars over the coming fiscal year. We will be able to solve the problem we face, therefore, [only if ]we adopt this plan.
the key word is only if...
only if means there is no way other than decease expenditure, an assumption not mentioned in the previous promise
so B is correct