What does multiprogramming enable a system to do?

Multiprogramming is a technique used in operating systems that allows multiple processes to be loaded into memory and executed concurrently, effectively enabling a system to run multiple processes at once. This approach improves system efficiency and resource utilization, as while one process is waiting for I/O operations to complete, the CPU can switch to another process that is ready to execute.

By leveraging multiprogramming, the system can maintain a high degree of responsiveness and throughput, as it minimizes the idle time of the CPU. This technique is particularly beneficial in environments where I/O operations can significantly delay process execution.

The other options do not accurately reflect the capabilities provided by multiprogramming. Running processes sequentially aligns more with batch processing, execution of a single process at a time limits the system's efficiency, and managing memory allocation is a separate function that can occur in both multiprogrammed and non-multiprogrammed environments. Thus, the correct answer highlights the fundamental capability of multiprogramming to execute multiple processes concurrently, enhancing overall system performance.