What type of communication is primarily associated with the Extremely Low Frequency (ELF) range?

The type of communication primarily associated with the Extremely Low Frequency (ELF) range is indeed one-way communication to submarines. ELF waves have the unique ability to penetrate deep into the ocean, making them effective for transmitting signals to submarines that are submerged at great depths. This capability is crucial for military operations, as it allows for secure communication without the need for submarines to surface, which can expose them to detection.

ELF communication is specifically designed to transmit information over long distances by using very low frequencies, which are less affected by water and other obstacles. This makes it an ideal choice for conveying important messages such as commands or navigational data to submarine fleets.

In contrast, other options like mobile phone communications and aviation communications utilize much higher frequency ranges and different technologies that are not suitable for the unique environmental conditions faced by underwater operations. Amateur radio operations also typically operate on higher frequencies that do not have the same penetrating capabilities as ELF. Consequently, the use of ELF for one-way communication to submarines stands out as the most accurate description of its primary application.