Which of the following describes what an Areal density measures?

Areal density refers specifically to the amount of data that can be stored in a given physical area of a storage medium, which is measured in bits per square inch on a disk. This measurement is important because it indicates how much data can be packed into a specific surface area of a disk, which directly affects the storage capacity and performance of hard drives and other disk-based storage devices. High areal density allows for greater memory capacity without needing to increase the physical size of the storage medium.

The other options do not accurately describe areal density. Data transfer speed relates to how quickly data can be read from or written to the storage medium, while data integrity refers to the accuracy and reliability of the information stored. Memory usage pertains to the amount of memory being utilized by applications or processes, which is a different concept altogether. Therefore, option C accurately defines areal density within the context of digital forensics and storage technology.