The correct option is C Gold
Gold does not react with air, water and other chemicals under normal conditions. As a result, it is more likely to be found in free state in nature. In fact not just gold, but even other metals like platinum, copper and silver can be found in free states in nature due to their less reactive nature.
Sodium is a highly reactive metal. Iron and zinc are moderately reactive metals. Hence, all these metals usually exist in combined state in nature.