According to general rule, a question mark is used at the end of a direct sentence whereas, indirect sentences are ended with a period.
The given sentence is an indirect sentence, thus a period should be used to end the sentence.
Thus, the correct answer will be Option A, no change.
Option B and D are incorrect, because a comma is never used at the end of a sentence and an exclamation mark is used to express strong feelings, high volume or for emphasis.