Analyze the relationship between 'BG Group' and 'natural gas' within the context of the input sentence.
Options: location of formation, product/material produced, owner of, employer

BRUSSELS, July 30 (Reuters) - European Union antitrust regulators will decide by Sept. 2 whether to approve Royal Dutch Shell (LSE: RDSB.L - news ) 's planned 47 billion pound ($73.25 billion) buy of BG Group (LSE: BG.L - news ) to become the world's top liquefied natural gas company.
product/material produced