The correct answer is A) Contactors contacts can handle heavier loads than relay contacts. This is correct because contactors are designed to handle higher current and power loads compared to relays. Contactors have larger contact surfaces and are built to withstand higher voltages and currents, making them suitable for controlling and switching heavy electrical loads such as motors, transformers, and other industrial equipment. In contrast, relays are typically used for lighter loads and control circuits, as their contacts are not designed to handle the same level of power. The other options are incorrect because they do not accurately represent the main difference between relays and contactors. Relays and contactors can be made from various materials, including silver and copper. The connection configuration (series or parallel) is not the defining characteristic, and contactors do not directly control voltage - they control the flow of current.