The correct answer for this question is 'Both A B' because both option A (hard drives) and option B (solid state drives) are widely used and considered the most common types of storage devices in modern computing. Hard drives are traditional storage devices that use spinning disks to store data, while solid state drives are newer, faster, and more reliable storage devices that use flash memory. By selecting 'Both A B', you acknowledge the prevalence and importance of both types of storage devices in the computing industry.