Final answer:
High-frequency EM waves can carry more information per unit of time compared to low-frequency waves due to their greater ability to support detailed modulations.
Step-by-step explanation:
High-frequency electromagnetic (EM) waves can carry more information per unit of time than low-frequency waves. This is because the higher the frequency of the radio wave used to carry data, the greater the detailed variation of the wave that can be carried by modulating it over each time unit. Consequently, more data can be transmitted per unit of time through high-frequency EM waves. For example, laser telephone transmission at visible frequencies, which are high in frequency, can carry far more conversations per optical fiber than conventional electronic transmission in a wire. In contrast, ELF radio communication with submarines typically uses lower frequencies, which are less capable of carrying large amounts of information.