Utilize the input text as a context reference, choose the right relationship between 'Tullow Oil' and 'Petroleum' from the options.
Options: owner of, product/material produced, member of, creator

Wed, Jul 15, 2015, 11:40 BST - UK Markets close in 4 hrs 50 mins When Will It Be Time To Buy Explorers Gulf Keystone Petroleum Limited, Enquest Plc And Tullow Oil plc?
product/material produced