What is the relationship between 'Talisman Energy' and 'Petroleum' in the context of the input sentence.
Options: chief executive officer, original broadcaster, product/material produced, operator

He then moved to Clyde Petroleum where he was managing director, then to Paladin Resources as chief executive until its acquisition by Talisman Energy (EUREX: 23554.EX - news ) in 2005.
product/material produced