Final answer:
A. parent table. In the context of non-relational databases, document databases and key/value databases are the correct choices, while parent and child tables are associated with relational databases.
Step-by-step explanation:
The types of non-relational databases from the options provided are document database and key/value database.
A document database, such as MongoDB, stores data in JSON-like documents and is often used for its flexibility and scalability. Key/value databases, like Redis, use a simple key to value mapping for storing data, which is highly optimized for scenarios where quick access to data is required.
Options A (parent table) and D (child table) are related to relational databases, where tables can have relationships with one another, such as parent and child tables, not non-relational databases.