The correct answer is: B. To allow people to use the computer.
An operating system is a software that manages computer hardware and software resources and provides a platform for running application programs. It acts as an interface between a user and the computer hardware, and it provides a number of services to programs, such as file management, memory management, and input/output (I/O) management.
The primary purpose of an operating system is to allow people to use the computer. It does this by providing a user interface that allows users to interact with the computer, and by providing a set of commands and utilities that allow users to perform tasks such as managing files, running programs, and accessing the Internet.
Option A is incorrect because the primary purpose of an operating system is not to make the most efficient use of the computer hardware. This is a secondary goal of an operating system, but it is not the primary goal.
Option C is incorrect because the primary purpose of an operating system is not to keep systems programmers employed. This is a tertiary goal of an operating system, but it is not the primary goal.
Option D is incorrect because the primary purpose of an operating system is not to make computers easier to use. This is a secondary goal of an operating system, but it is not the primary goal.