Computers use the _____ number system to store data and perform calculations.

The correct answer is D. Binary.

A binary number system is a numeral system with two as its

base. It is the simplest numeral system, and the only one where each digit can have only two values: 0 and 1. This makes it well-suited for use in computers, which can only store and process two values: on and off.

A decimal number system is a numeral system with ten as its base. It is the most common numeral

system in use today, and is used in everyday life for counting, measuring, and calculating.

A hexadecimal number system is a numeral system with sixteen as its base. It is often used in computer programming, as it is a convenient way to represent binary numbers.

An octal number system is a numeral system with eight as its base. It is sometimes used in computer programming, but is less common than hexadecimal.

None of these is the correct answer.