Final answer:
An operating system that resides in the firmware of a mobile device is referred to as an embedded OS, like iOS or Android, which manage the functions of the device efficiently and reliably.
Step-by-step explanation:
On a mobile device, the operating system resides in firmware, and is therefore, a/an embedded OS. An embedded operating system is a type of system that is specifically designed to manage and run the computing functions within non-computer devices like smartphones, tablets, and other specialized hardware. It generally has limited resources, is optimized for efficiency and runs with a high degree of reliability since it often performs crucial tasks. For example, iOS on iPhones and Android on various mobile devices are both considered embedded operating systems because they are built into the hardware of the device and are tailored to manage its functions.