Answer: B
Correct answer: was
Furniture is uncountable and takes a singular verb: the furniture was replaced. It has no plural, so furnitures is also wrong, and it cannot take a or an. To refer to one item a unit noun is required: a piece of furniture, three items of furniture. It belongs to the group of nouns countable in many Indian languages but not in English: information, advice, luggage, baggage, machinery, stationery, equipment, scenery, poetry, evidence, bread and news. Each takes a singular verb and is quantified with much and less. The singular conference room in the intervening phrase has no bearing on the agreement; the subject remains the furniture. The passive is correctly used, since the furniture received the action rather than performing it.