Why is a touchscreen called a combined device?

Correct answer: It displays output and also accepts input through touch

The governing concept is the distinction between input and output devices. A touchscreen displays text, images, menus, and results, so it performs an output function. It also detects a user’s touch and converts that action into commands or selections, so it performs an input function. Hence option C is correct. Storage, sound production, and power supply are not the reason it is called a combined device.