Utilize the input text as a context reference, choose the right relationship between 'Petrobras' and 'gas' from the options.
Options: owned by, director/manager, currency, product/material produced

Thu, Jul 2, 2015, 03:30 BST - UK Markets open in 4 hrs 30 mins Brazil's Petrobras sells $25 million stake in oil, gas field Reuters – 1 hour 57 minutes ago 1,803.50 +17.00
product/material produced