In this task, you're given an ambiguous question (which can be answered in more than one way). Your task is to provide one question which clarifies the input question and it has one unique answer, and also provide an answer to the generated question. Generated question and answer should be separated with a new line.

Example Input: Where does the savannah river begin and end?
Example Output: Where does the savannah river begin? 
 confluence of the Tugaloo River and the Seneca River

Example Input: Who sang must be talking to an angel?
Example Output: Which duo sang must be talking to an angel? 
 Eurythmics

Example Input: When did coal become a major energy source?
Example Output:
During what time period did coal become a major energy source globally? 
 19th and 20th centuries