What is TRUE about Primary Key?Question 9Answera.An entity can only be uniquely identified by using the first keyb.All of the abovec.Primary keys are selected for each entity according to its requirements and developersd.From these lists, the most appropriate key becomes a primary key

The correct answer is c. Primary keys are selected for each entity according to its requirements and developers.

Here's why:

a. An entity can be uniquely identified by any key that is unique, not just the first key.

b. "All of the above" cannot be true because option a is incorrect.

c. This is true. Primary keys are chosen based on the specific needs and requirements of each entity. Developers often make this decision.

d. While it's true that the most appropriate key is chosen as the primary key, this statement is too vague to be the best answer. The process of selecting a primary key is more complex and involves considering the specific requirements of each entity, as stated in option c.