The correct answer is option 3 - tin. Bronze is an alloy composed primarily of copper and tin. Alloys are a combination of different metals or a metal with a non-metal. In the case of bronze, it is made by mixing copper with tin in various proportions.

Option 1 - Nickel: Nickel is not a component of bronze. While nickel can be alloyed with copper to form another alloy called cupronickel, it is not the primary metal in bronze.

Option 2 - Iron: Iron is not a component of bronze either. Bronze is distinct from iron-based alloys such as steel.

Option 4 - Aluminium: Aluminium is also not a component of bronze. Bronze has been used since ancient times, while aluminium was only discovered relatively recently and was not available to ancient civilizations.

Therefore, the correct component of bronze, as stated in option 3, is tin.