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

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