Take context from the input text and decide on the accurate relationship between 'Mary Barra' and 'General Motors' from the options provided.
Options: operator, location of formation, employer, stock exchange

DETROIT (Reuters) - General Motors Co (GM.N) Chief Executive Mary Barra said the automaker plans new efforts to capitalize on the connectivity built into its cars, expanding car sharing services, offering more autonomous driving features and enabling services through smartphone apps.
employer