Final answer:
Infrared signals are used for (2) short-range communication due to their properties and interactions with the atmosphere, but they are not ideal for long-range communication like interstellar messages, wherein microwaves are preferred.
Step-by-step explanation:
Infrared signals are primarily used for short-range communication. These signals are part of the electromagnetic spectrum and are characterized by frequencies just below the visible light, meaning they are infrared with respect to the color red. Infrared technology is often leveraged for its capability to be used in remote controls, wireless data transfer within a short range, such as in remote keyless system (RKS) for cars and other consumer electronics.
Additionally, infrared is well-absorbed by water and other molecules in Earth's atmosphere, providing good interaction with the environment for applications like thermal imaging.
Due to the absorptive properties of interstellar gas and dust, and the need for a line of sight for communication, infrared is not ideal for long-range communication such as interstellar messages. Microwaves, having the ability to carry information effectively over long distances, are better suited for this purpose, especially since most satellite communication and long-distance terrestrial communication utilize microwaves.