Fill in the blank with the most appropriate word. _____ other day I had a letter from my friend.
The correct option is D The
An/A' is used as an indefinite article for a thing or person when the reader doesn't know which one we are referring to out of many nouns. It states the random nature of the subject.
'The' is used as a definite article for a thing or person when the reader knows which one we are exactly referring to. It states the specific nature of the subject.
Option C is correct as 'The' is used with words which have been mentioned previously. The readers are aware of that day. Option A is incorrect as 'A other day' sounds illogical and is grammatically incorrect. Option B is incorrect because 'An other day' implies any random day that the readers are unaware of. Option D is incorrect as an article is required in the blank to give meaning to the sentence.