What is the relationship between BG Group and Royal Dutch Shell in the context of the input sentence. Choose an answer from: 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.

LONDON, Sept 8 (Reuters) - A look at valuations illustrates how regulatory concerns and stubbornly low energy prices have stoked investor anxiety over Royal Dutch Shell (Xetra: R6C1.DE - news ) 's planned takeover of British rival BG Group (LSE: BG.L - news ) .

Answer: parent_organization