Buzz was a subsidiary of the flag carrier airline of which country from 2000 to 2004?
Buzz (airline):  It operated from 2000 until 2004 as a subsidiary of KLM and then Ryanair. KLM: KLM Royal Dutch Airlines, legally "Koninklijke Luchtvaart Maatschappij N.V.", is the flag carrier airline of the Netherlands.
Netherlands