If parent company is from US following US GAAP, subsidiary from Germany should follow US GAAP or IFRS?

Question

German Subsidiary of US company has the option of following US GAAP? or  IFRS is must?

Answer 1

The subsidiary MUST prepare financial statements on the applicable financial reporting framework, which for germany is IFRS (as far as I'm concerned).(for statutory audit)

However for internal purpose it MAY also prepare the financial statements on GAAP. But statutory auditor won't audit that financial statements.