Explanation

Turkey is correct because it has been actively involved in recent discoveries of natural gas reserves along the Black Sea coast. Russia is incorrect as while it has resources, Turkey's recent focus on this area makes it the better answer for 'recently'. Qatar is incorrect because it is known for its large gas fields but not specifically for a major recent discovery on the Black Sea coast. Greece is incorrect as it is not primarily associated with the most recent large natural gas discoveries in that specific region.