Utilize the input text as a context reference, choose the right relationship between BG Group and Royal Dutch Shell 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.

The three largest oil companies BP, Royal Dutch Shell (LSE: RDSB.L - news ) and BG Group (LSE: BG.L - news ) alone make up 13.3pc of the index by weight.

Answer: parent_organization