The correct answer is option 4: nickel. Sudbury, located in Canada, is known for its large-scale production of Nickel. Nickel is a metallic element that is commonly used in various industries, such as stainless steel production, electronics manufacturing, and battery technology. Sudbury has abundant nickel reserves and is home to several nickel mines and processing facilities. The city`s economy heavily relies on the production and export of nickel. It is important to note that while Sudbury is known for nickel production, it also produces other minerals and metals, but on a smaller scale compared to nickel. Therefore, option 4 is the most accurate and appropriate answer in this context.