Merger and acquisition activity in the energy sector has been rekindled as company valuations slumped along with oil prices, highlighted by Royal Dutch Shell (Xetra: R6C1.DE - news ) 's $70 billion bid to acquire BG Group (LSE: BG.L - news ) earlier this year.
Analyze the relationship between 'BG Group' and 'Royal Dutch Shell' within the context of the input sentence.
Options: member of, stock exchange, chief executive officer, parent organization