Answer:
They would be filing Option A: "Single" in 2018.
Step-by-step explanation:
A taxpayer would choose the filing status that will result in the lowest tax. Filing status determines the rate at which income is taxed. The five filing statuses are: single, married filing jointly, married filing separately, head of household, and qualifying widow(er) with dependent child. In case Ben and Sarah are legally divorced, Single is status that is chosen for filing status. Other status is either for married people or for widow. Thus, out of the given options, Option A is the correct answer.