The Houston–The Woodlands–Sugar Land MSA's gross domestic product (GDP) in 2012 was $489 billion, making it the fourth-largest of any metropolitan area in the United States and larger than Austria's, Venezuela's, or South Africa's GDP. Only 26 countries other than the United States have a gross domestic product exceeding Houston's regional gross area product (GAP). In 2010, mining (which consists almost entirely of exploration and production of oil and gas in Houston) accounted for 26.3% of Houston's GAP up sharply in response to high energy prices and a decreased worldwide surplus of oil production capacity, followed by engineering services, health services, and manufacturing.
Try to answer this question if possible (otherwise reply "unanswerable"):  Under what category does ocean exploration fall?
unanswerable