Which of the following describes a personal digital assistant (PDA)?

A personal digital assistant (PDA) is specifically designed as a handheld device for managing personal information. This includes functionalities that help users organize their schedules, take notes, store contacts, and sometimes access the internet. The primary aim of a PDA is to assist users in personal productivity tasks in a compact and portable format.

In contrast, other choices describe devices that serve different purposes. A portable computer with advanced features suggests a more powerful laptop or ultrabook, which typically offers extensive capabilities beyond personal information management. A desktop computer for heavy processing tasks indicates a stationary setup primarily used for demanding computational work, lacking the portability that characterizes a PDA. Lastly, a large computer designed for scientific calculations refers to powerful systems intended specifically for high-level computations, which is not relevant to the everyday organizational functions associated with a PDA. Thus, the correct description aligns with the essential characteristics and functions of a PDA.