Final answer:
The second normal form requires each attribute to be functionally dependent on the entire primary key for tables with composite primary keys, thereby reducing data redundancy and improving data integrity.
Therefore the correct answer is c.) each attribute in a table should be functionally dependent on the primary key.
Step-by-step explanation:
The criterion introduced in the second normal form (2NF) addresses the need for each attribute in a table to be functionally dependent on the entire primary key when the primary key is composed of multiple columns. This means that all non-key attributes must be dependent on the full set of the composite primary key, not on just a part of it. Hence, the correct answer to the question, 'What is introduced as a criterion of a table in second normal form?' is c.) each attribute in a table should be functionally dependent on the primary key.
Choosing the correct organization of data can lead to benefits, such as reduced redundancy and improved data integrity. Typically, in 2NF, one would aim to separate data into different tables to ensure that each piece of data is stored only once, thereby reducing redundancy. This is achieved by identifying and exploiting functional dependencies, where one attribute uniquely determines another.
If a decision is made to switch between tables while organizing the data, it would be done to improve database normalization which helps to minimize redundancies. For instance, to adhere to the principles of 2NF, one might separate data related to customer orders from data about the customers themselves if the order data does not rely on the full composite key.
Also, as per good data representation practices, table columns or graph axes should be labeled with Quantity/units to indicate the units of the quantity in the table or axis.