Which of the following metals is stored under oil to prevent it from reacting with air and moisture?

Sodium is a highly reactive alkali metal that reacts vigorously with both oxygen in air and with water. It is therefore stored under oil (usually kerosene or paraffin oil) to prevent contact with air and moisture. Iron and aluminium are much less reactive and do not require such storage, while calcium is stored under oil but sodium is the classic example most commonly cited.