Which part of the computer is responsible for modifying data?

The microprocessor is the correct answer because it serves as the central processing unit (CPU) of the computer, where most data processing takes place. It executes instructions, performs calculations, and modifies data as directed by the software. Essentially, the microprocessor is the brain of the computer, managing and manipulating data through a series of logical operations.

While circuit boards serve as the physical platform that hosts various components of the computer, they do not directly modify data themselves. Input devices are responsible for sending data to the computer for processing but do not engage in data modification. Peripheral devices, which can include a variety of external components (like printers or external drives), also do not alter data; rather, they serve additional functions that can support or expand the computer's capabilities. Therefore, the microprocessor is the key component responsible for modifying data within a computer system.