The correct answer is D. 24153.
The first option, 31542, is incorrect because it does not contain the word “myself”. The second option, 21435, is incorrect because it does not contain the word “question”. The third option, 25413, is incorrect because it does not contain the word “I”. The fourth option, 24153, is the correct answer because it contains all five words in the correct order.
The word “solved” comes first because it is the most important word in the question. The word “I” comes second because it is the subject of the sentence. The word “question” comes third because it is the object of the sentence. The word “myself” comes fourth because it is the object of the preposition “by”. The word “this” comes last because it is the object of the verb “solved”.