An operating system

is the chief hardware unit in a computer.
is loaded into the computer each time it needs to carry out an operation.
ensures that programs will not run on the computer at the same time.
allocates resources like memory to programs that are running.
all of the above.
allocates resources like memory to programs that are running

Allocates resources like memory to programs that are running

Explanation:

The Operating System (OS) works as an intermediary between the computer hardware and the programs or applications. It is a software that allocates resources to processes and manages Input and Output (I/O) devices. Some major examples of the OS are Linux, Microsoft Windows, and macOS.

The types of Operating Systems include the following:

Single-tasking and Multitasking: Single-tasking OSes allow only one program to be executed at a given time, here, no other program will run on the OS until the current program ends or is terminated. Multi-tasking OSes allow more than one program to run concurrently, system resources are shared among these programs to enable them to function at the same time.Single User and Multi-user: Single User OSes are that are only available to a user, system resources and computer programs are made available to just an individual. Multi-user OSes allow multiple users to use the machine, disk space among other resources are shared among all users.Distributed OS: Individual computers are controlled or managed by the OS to function as a single unit. This usually comes in handy when dealing with massive computational problems and analysis.Templated OS: This is generally used in Virtualization, where virtual machines are created and templated OSes are used.Embedded OS: This OS is used for embedded systems, they are designed to operate within a specific machine and use limited resources.