Which of the following devices fits in the palm of your hand?

A Personal Digital Assistant (PDA) is a handheld device designed to manage personal information. It typically fits comfortably in the palm of your hand, making it portable and easy to use on the go. PDAs are used for tasks like scheduling, note-taking, and basic communication, and their compact design allows for significant mobility and convenience.

In contrast, mainframe computers, supercomputers, and desktop computers are much larger in size and are not designed for handheld use. Mainframe computers are used for bulk data processing and are typically housed in dedicated facilities. Supercomputers are even larger, designed for complex scientific calculations and simulations, often taking up entire rooms. Desktop computers are built to stay on a desk and require a significant amount of space for their components and peripherals. Therefore, the correct answer emphasizes the unique portability feature of PDAs compared to larger computing devices.