Refer to the input text as context and select the correct relationship between 'David Thodey' and 'Telstra' from the available options.
Options: position held, employer, owner of, parent organization

David Thodey engineered a stunning turnaround at Telstra , extending its dominant position in the mobile sector, negotiating lucrative agreements with the government (twice) over the National Broadband Network, selling off non-core assets and cutting expenses.
employer