In the context of the input sentence, determine the relationship between 'Gail Kelly' and 'Westpac'.
Options: employer, subsidiary, legal form, platform

Nic Walker Share on twitter by Sue Mitchell South African retailer Woolworths Holdings has turned to former Westpac chief executive Gail Kelly to help transform itself into a leading southern hemisphere retailer after last year's $2.1 billion acquisition of David Jones.
employer