What is the relationship between 'Brian Hartzer' and 'Westpac' in the context of the input sentence.
Options: stock exchange, chief executive officer, owner of, employer

Louie Douvis Share on twitter by James Eyers Westpac Banking Corp's chief executive Brian Hartzer has been urged to set out a plan for cost reductions at the bank's strategy update on Monday, including reducing the number of branches, which has been inflated since the acquisition of St George during the financial crisis.
employer