The correct answer is A. rather well.
The sentence is about someone who has developed their ability to converse in Marathi. The word “rather” is used to indicate that the person’s ability is good, but not excellent. The word “well” is used to indicate that the person’s ability is good. Therefore, the correct answer is A. rather well.
The other options are incorrect because they do not accurately reflect the meaning of the sentence. Option B, rather better, indicates that the person’s ability
is better than good. Option C, fairly well, indicates that the person’s ability is not very good. Option D, good rather, is grammatically incorrect.