What type of storage device is a smartphone classified as?

A smartphone is classified as a full-feature personal computer (PC) because it integrates various functionalities typically found in a traditional PC, such as processing power, software applications, and connectivity to the internet.

Smartphones possess an operating system that allows users to run a variety of applications, perform multitasking, and manage files similarly to a full-feature PC. They also support a range of features like cameras, GPS, and touchscreens that all contribute to their capability as a computing device.

In contrast, the other options refer to different categories of technology. Secondary storage devices generally refer to hard drives or SSDs used to store data, removable storage devices often refer to USB drives or SD cards that can be easily detached, and optical storage devices involve media like CDs and DVDs that store data using laser technology. These terms do not encompass the multifunctional nature and capabilities of a smartphone.