Which of the following computer components can be built using only NAND gates?

The ALU (Arithmetic Logic Unit) can be built using only NAND gates because NAND gates are universal gates, meaning they can be used to construct any other gate. Since the ALU is responsible for performing arithmetic and logical operations in a computer processor, it requires various gates such as AND, OR, and NOT gates. By using a combination of NAND gates, these other gates can be constructed, allowing for the construction of an ALU. This highlights the versatility and power of NAND gates in digital circuit design.