LONDON, Sept 2 (Reuters) - Royal Dutch Shell (Xetra: R6C1.DE - news ) gained EU approval on Wednesday for its $58 billion acquisition of Britain's BG Group (LSE: BG.L - news ) , the second of four key markets needed to clear the deal, but faced a slight delay in securing a decision in Australia.
In the context of the input sentence, determine the relationship between 'BG Group' and 'Royal Dutch Shell'.
Options: headquarters location, publisher, position held, parent organization