Single-mode fiber is designed for long-distance transmission with a smaller core that allows only one mode of light to propagate, which reduces signal attenuation and provides higher bandwidth over longer distances. Multimode fiber, with its larger core, supports multiple light modes, but is more prone to signal loss and dispersion over long distances, making it suitable for shorter runs. Copper cables are typically not used for long-distance data transmission due to signal loss and electromagnetic interference. Coaxial cable, while it can be used for certain types of network connections, does not have the same capacity for long-distance transmission as single-mode fiber.