Converting a yes/no question from direct to indirect speech requires three changes: the reporting verb "said to" becomes "asked," the question format is replaced with a statement introduced by "if" or "whether," and the verb tense shifts one step into the past. Testing each option against all three rules identifies the correct conversion.
Only one option changes the reporting verb to "asked," reframes the question with "if," and shifts the tense correctly, all at the same time.
Therefore, the correct answer is The little girl asked her mother if the sun rose in the East.