What is the relationship between Brian Hartzer and Westpac in the context of the input sentence. Choose an answer from: product/material produced; manufacturer; distributed by; industry; position held; original broadcaster; owned by; founded by; distribution format; headquarters location; stock exchange; currency; parent organization; chief executive officer; director/manager; owner of; operator; member of; employer; chairperson; platform; subsidiary; legal form; publisher; developer; brand; business division; location of formation; creator.

As analysts including Mr Mott and Mr Martin probed Westpac chief executive Brian Hartzer on Monday at the briefing over the accounting treatment, Mr Hartzer assured them there is nothing tricky about the policy.

Answer: employer