Explanation:

Computers are digital devices, meaning they process and store information in discrete, quantifiable units. Option (a) 'analog data' refers to continuous signals (like sound waves or light intensity) that vary smoothly over time. While computers can *process* analog data, they first convert it into a digital format for storage and manipulation. Option (b) 'digital data' is information represented by discrete values, typically binary digits ($0$s and $1$s). This is how all information (text, images, audio, video, programs) is stored in a computer. This is the correct answer. Option (c) 'modem data' refers to data transmitted via a modem, which is a device, not a fundamental storage format. Option (d) 'watts data' is nonsensical; Watts ($\text{W}$) is a unit of power. Option (e) 'none of these' is incorrect as option (b) correctly identifies the storage format.