NoSQL databases typically store what type of data?

NoSQL databases are designed to handle various types of unstructured or semi-structured data that do not fit neatly into the relational model of tables and rows. They offer flexibility in how data is stored and accessed, which makes them suitable for handling diverse data formats.

The correct answer acknowledges that NoSQL databases can store files and do not require the use of traditional table structures. This flexibility allows them to accommodate a range of data models, including key-value pairs, document-oriented formats, column families, and graphs, enabling efficient access and processing of large volumes of data.

In contrast to the correct answer, other options refer to more traditional data storage methods. While tables and rows are foundational to relational databases, flat files represent a simpler way of storing data that still presupposes a fixed structure, which conflicts with the dynamic nature of NoSQL systems. The mention of hierarchical data only suggests a limitation that doesn't reflect the broader capabilities of NoSQL databases, which can handle multiple data formats beyond just hierarchical structures. In summary, the capacity of NoSQL databases to manage varied data forms without a strict schema is what makes the identified answer accurate.