What is closed source software?

• A. Free software that anybody can modify
• B. Software that runs on mobile devices only
• C. Programs that keep all or some of the code hidden, enable developers to control and profit from programs created
• D. A USB drive storing data

Answer: (C)

Closed source software is software whose source code is not shared with the public. The code is kept private so the original developers maintain control over how the program is used, modified, and distributed, and they typically monetize it through licenses or sales. This means users can’t freely study or alter the code. The description reflects that by noting that the code is hidden and developers can control and profit from the program. Other options don’t define this idea: software that runs on mobile devices is not about access to code, and a USB drive is just storage, not a type of software.