Which of the following statements is true about a column in a table of a relational database?

A column with naturally occurring unique values is indeed a good choice to be the primary key because primary keys uniquely identify each record in a table. This characteristic is fundamental in ensuring that each entry can be retrieved efficiently and prevents duplicate entries from existing within the database. When a column contains unique values, it maintains the integrity of the database by making it easier to establish relationships with other tables and supporting functions like indexing and searching.

The other options do not accurately reflect the standards of relational databases. For instance, columns typically store a single data type, reinforcing data integrity and consistency, while columns can have restrictions on blank entries depending on the database schema, and numeric values are not a requirement for all columns, which can encompass various data types such as strings, dates, and Booleans.