Answer:
D. Binary
Step-by-step explanation:
Computer hardware parts are built on transistors, small electrical devices that switch electrical signals and amplify power. The CPU (Central Processing Unit), the "brain" of the computer, has billions of tiny transistors alone.
These transistors read binary, a code made up of 1's and 0's. This code tells what the computer to do.
CSS, HTML, and HTML 5 apply to web pages and web page designs, not code for the computer.
The OS (operating system) that your computer runs is coded in C++ (Windows) or C (Linux)