Utilize the input text as a context reference, choose the right relationship between Hindustan Petroleum and Petroleum from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

State-owned fuel retailers -- IOC, Bharat Petroleum Corp (BPCL) and Hindustan Petroleum Corp (HPCL) -- revise petrol and diesel prices on 1st and 16th of every month based on average imported cost and rupee-dollar exchange rate in the previous fortnight.

Answer: product_or_material_produced