original question: Which engine was designed by [Rolls-Royce Holdings]?
answer: rolls-royce merlin
answer type: Engine.
auxiliary information: Rolls-Royce Holdings plc is a British multinational public holding company that, through its various subsidiaries, designs, manufactures and distributes turbine-based power systems for aviation and other industries. Rolls-Royce Holdings is headquartered in City of Westminster, London. It is the world‚Äôs second-largest maker of aircraft engines, and also has major businesses in the marine propulsion and energy sectors. Rolls-Royce was the world's 16th-largest defence contractor in 2011 and 2012 when measured by defence revenues. It had an announced order book of ¬£71.6 billion as of January 2014. Rolls-Royce is listed on the London Stock Exchange and is a constituent of the FTSE 100 Index. As of June 2013, it had a market capitalisation of ¬£22.22 billion, the 24th-largest of any company with a primary listing on the London Stock Exchange.
[Rolls-Royce Holdings] is known for designing what engine?