What is the primary characteristic of a USB drive?

The primary characteristic of a USB drive is that it is a flash memory storage device that plugs into a USB port. This feature allows USB drives to serve as portable storage solutions, enabling users to easily transfer and store data across various computers and devices. USB drives are compact and provide a plug-and-play interface, making them user-friendly and convenient for daily data tasks.

Other options describe different types of devices. For instance, options referring to wireless internet devices and optical storage mediums pertain to different technologies entirely, such as Wi-Fi devices or CDs and DVDs, which use lasers to read and write data. The reference to a battery storage device for portable electronics indicates another category of technology related to power management rather than data storage, highlighting the distinctive purpose and functionality of a USB drive as a data storage medium.