In First Normal Form (1NF), what is required for each row in a table?

In First Normal Form (1NF), the primary requirement is that each row in a table must be unique, which means that no two rows can be identical. This uniqueness is typically enforced by a primary key, which is a specific column (or a combination of columns) that ensures each entry can be distinguished from the others.

1NF focuses on ensuring that the table structure is such that each piece of data is atomic, meaning that each field contains indivisible values. While the other choices touch on different aspects of database normalization and design, they do not align with the core requirement of 1NF. For instance, having multiple values in a column (as suggested in the first option) would violate the atomicity principle of 1NF. The reference to non-primary keys being duplicated is also not pertinent because 1NF addresses the uniqueness of entire rows rather than just certain columns. Lastly, although creating multiple tables is a concept in higher forms of normalization, it is not a prerequisite of 1NF.

Therefore, the requirement for each row to be unique is foundational for a table to meet the criteria of First Normal Form.