What is a defining feature of block storage?

Block storage is characterized by being divided into fixed-sized blocks, each of which can be managed and accessed independently. This feature allows for rapid retrieval and management of data, making it particularly suitable for workloads that require high performance and low latency, such as databases and virtual machines.

By addressing data in blocks, this type of storage can optimize input/output operations, which is critical for applications needing fast processing speeds. Each block can also be configured with different performance characteristics, giving users flexibility based on their specific needs.

In contrast, other features or characteristics present in the choices do not align with the core function of block storage. For instance, accessing through APIs, while possible, is not exclusivity to block storage and can be seen in other storage types as well. Similarly, block storage is not primarily designed for unstructured data; that is generally the domain of object storage. Lastly, while cost might vary between different storage solutions, it does not define the fundamental nature of block storage itself. Therefore, the division into blocks and the consequent management efficiency is what distinctly identifies block storage.