The correct answer is Option D.
We are to complete the given sentence from the most suitable word from the given options.
In the given sentence, it is implied that because a new management is taking over the company, the future of the company is unknown. Just as during uncertain times an answer to a question is unknown, the future of the company is unknown. Hence there is a relation between the company's future and a question. Therefore, the word that correctly completes the sentence is Option D.
There is a big question mark hanging over the company's future because the future is unknown.
Option A: THOUGHT is the incorrect option because it is not correct in the given context of the sentence.
Option B: GOSSIP is casual talk which also does not go with the meaning of the sentence. Hence it is incorrect.
Option C: DISCUSSION means 'debate or talk'. A company's future cannot depend on a discussion. So, it not the correct answer.
Hence, Option D is the correct answer.