In common usage, a device is best defined as:

• A. A plan
• B. A plot
• C. A contraption used to perform specific tasks
• D. A document

Answer: (C)

The main idea being tested is how we use the word device in everyday language. A device is typically a tool or gadget—a contraption or instrument designed to perform a specific task, often mechanical or electronic. That sense fits common usage, as in a safety device, a recording device, or a kitchen device. It isn’t a plan or plot, which are about ideas and schemes for doing something, nor a document, which is a written record. So the best fit is a contraption used to perform specific tasks.