What is the relationship between 'Xbox 360' and 'Microsoft' in the context of the input sentence.
Options: location of formation, chairperson, position held, developer

Microsoft ( MSFT.O ) added 1.2 percent to $20.76 after the software maker said it sold 28 million units worldwide of its Xbox 360 video game console through the end of 2008, extending the Xbox's lead over rival Sony Corp's ( 6758.T )( SNE.N ) PlayStation 3.
developer