Processes are assigned portions of __________ to use during operation.

Processes are assigned portions of main memory to use during operation because main memory, or RAM, is where the operating system loads running processes and their associated data. Each process requires a dedicated space in memory to execute its instructions and store temporary data. This allocation allows the operating system to manage resource utilization effectively among various running processes and ensures they do not interfere with each other's memory space, which is essential for system stability and security.

In contrast, folders/directories are used for file storage and organization, not directly tied to process execution. Hardware devices refer to physical components that execute specific tasks, such as CPU or I/O devices, which are used by the processes but are not portions of memory allocated to them. Access control relates to permissions and security measures governing who can access certain resources, rather than concerning itself with the memory requirements of running processes.