Answer : 3. "burning"
Explanation :

The process of copying files to a CD is called burning.

1. The full form of CD ROM is Compact Disc Read Only Memory. It is a storage device that can contain data as well as media files.

2. Burning is the process of copying media files like movies, pictures, etc. to a CD.

3. Ripping is the process of copying media files from a CD to a computer.

4. Zipping is the process that compresses a file into a folder to reduce the space used.

5. Digitization is converting information into digital format.