What property of sound makes infrasound distinct from ultrasound?

The distinction of infrasound from ultrasound primarily lies in its frequency range. Infrasound refers to sound waves that have frequencies below the standard threshold of human hearing, which is typically around 20 Hz. Frequencies lower than this are classified as infrasound.

The correct choice highlights that infrasound has a lower frequency than what can be heard by human beings. This property differentiates it from ultrasound, which consists of sound waves at frequencies higher than 20 kHz, also beyond the range of human hearing.

Infrasound is often used in various applications, such as monitoring natural events like earthquakes, while ultrasound has uses in medical imaging and industrial testing due to its higher frequencies. The other options are less accurate since they either misrepresent the frequency ranges or imply capabilities that do not apply universally to either category of sound.