2. Please answer in your ownwords a. Explain the concept of physical data independence, and its importance in database systems. b. What is a transaction? Define ACID and provide a brief description of each What is integrity? Describe d. Differentiate between an entity and an entity set. Differentiate between a relation and a relationship. Can a relationship be represented by a relation? e. f. What is the difference between a super key, a candidate key, and a primary key