Based on an MOU concluded with PTT on information exchange and joint study regarding liquefied natural gas (LNG) as well as natural gas supply, Osaka Gas Group has for some years been stepping up cooperation with the PTT Group through operational and technical support for PTT’s LNG receiving terminal.
Take context from the input text and decide on the accurate relationship between 'Osaka Gas' and 'liquefied natural gas' from the options provided.
Options: founded by, currency, product/material produced, chairperson