The correct answer is: B. brought about disharmony.
A rift in the lute is a metaphor for a break in harmony or unity. In this case, the arrival of the mother-in-law has caused disharmony in the family. This is because she is a new person who is not familiar with the family’s dynamics, and she may have different expectations and values than the rest of the family. This can lead to conflict and tension, as the family tries to adjust to her
presence.The other options are incorrect because they do not accurately reflect the meaning of the phrase “a rift in the lute.” Option A, “caused unnecessary worries,” is incorrect because it does not suggest that there is any conflict or tension in the family. Option C, “caused a pleasant atmosphere,” is incorrect because it suggests that the arrival of the mother-in-law has had a positive impact on the family, which is not the case. Option D, “brought about a disciplined atmosphere,” is incorrect because it suggests that the mother-in-law has brought order and structure to the family, which is also not the case.