Answer:
Binary
Step-by-step explanation:
For a computer to understand data and programs, they must be converted to binary.
Binary is a base-2 numbering system that uses only two digits, 0 and 1, to represent information. It is the most fundamental way in which computers process and store data, as it can be easily translated into electrical signals that can be understood by computer circuits.
Therefore, the correct answer is binary. Hexadecimal, octal, and decimal are other numbering systems that can be used to represent data, but they are not used directly by computers in the same way that binary is.