On Monday, it froze a trading account linked to Citadel Securities, a unit of the U.S. group that also owns hedge fund Citadel LLC - the first time in the crackdown that a foreign firm confirmed one of its Chinese accounts had been suspended.
Take context from the input text and decide on the accurate relationship between 'Citadel LLC' and 'hedge fund' from the options provided.
Options: operator, industry, director/manager, chairperson