Utilize the input text as a context reference, choose the right relationship between Alon USA 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.

Based in Dallas, TX, Alon USA Energy is an independent refiner and marketer of petroleum products, with primary operations in the South Central, Southwestern and Western regions of the U.S.

Answer: product_or_material_produced