Hardware and software work to allow a user to perform a function.
independently
jointly
repeatedly
separately

Answer

Hardware and software work jointly to allow a user to perform a function.

Explanation

Software and hardware work hand in hand to process the input. The Central Processing Unit (CPU) performs the processing of the input and provides an output through a fetch-execute cycle. In a simple language, let’s take this relationship as riding a bike. The bike and the body are the hardware whereas the knowledge of how to ride the bicycle and where to ride to is the software.

The right choice is Jointly

Computer software and computer hardware work together to process the input. Computer software controls computer hardware. In order for a computer to effectively manipulate data and produce useful output, its hardware and software must work together. These two components are complementary and cannot work independently of one another. Computer hardware is any physical device used in or with your machine, whereas software is a collection of code installed onto your computer's hard drive

that would be my answer.