Which type of computer is characterized as large and high-speed, often supporting multiple workstations?

The correct choice is the mainframe computer. Mainframes are specially designed to process large volumes of data at high speeds, making them ideal for applications requiring substantial computation power and the ability to handle numerous transactions simultaneously. They are typically utilized by large organizations, such as banks or governmental institutions, that need to support many users at once across various workstations.

Mainframes excel in environments that demand reliability, efficiency, and the capacity to manage extensive data sets, which is essential in sectors where data integrity and throughput are critical. They are engineered to operate continuously and can handle massive data processing tasks, which sets them apart from other types of computers.

While servers do also support multiple users and can handle high workloads, they generally do not achieve the same scale of processing speed and power as mainframes. Personal computers are typically designed for individual use and lack the capabilities of mainframes, particularly in terms of scalability and processing power. Embedded systems are specialized computers designed for specific control tasks and do not fit the description of supporting multiple workstations in the same manner that mainframes do.