Final answer:
The correct sentence is B) The teacher asked, "Who can solve this math problem?" where the question mark is placed inside the closing quotation marks, as it is part of the quoted question.
Step-by-step explanation:
The sentence with the correct placement of quotation marks is "The teacher asked, "Who can solve this math problem?"" When it comes to using quotation marks and punctuation, the rule is that question marks and exclamation points go inside the quotation marks if they are a part of the quoted material.
In this case, the question being asked by the teacher is part of the quotation, so the question mark should be placed before the closing quotation marks. Sentence A is incorrect because it places the question mark outside of the quotation marks when it should be inside. Sentence C lacks the comma after "asked," which should be used to separate the signal phrase from the quoted question.