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.
Utilize the input text as a context reference, choose the right relationship between 'Citadel LLC' and 'hedge fund' from the options.
Options: operator, director/manager, chairperson, industry