Final answer:
Prime attributes are part of any candidate key of a relation, while nonprime attributes are not included in any candidate key. Option d) correctly states the distinction between the two.
Step-by-step explanation:
To distinguish between prime and nonprime attributes in the database schema, we look at the participation of the attributes in candidate keys. Prime attributes are those attributes that are part of any candidate key of a relation. In contrast, nonprime attributes, also known as non-key attributes, are attributes that are not part of any candidate key.
Therefore, the correct option is:
Prime attributes are key attributes; nonprime attributes are not part of any candidate's key
For example, consider a table with attributes A, B, and C, where A and B together form a candidate key. In this case, A and B would be considered prime attributes, while C would be a nonprime attribute.