1. What does "physical data independence" mean? Give an example using SQL and explain why it is important to database systems. 2. Explain the difference between database and database management system. 3. A vehicle registration database has the following fields: vin (vehicle identification number), tag_number, make, model, year, color. Which field or fields can be considered as superkey(s)? Which field or fields can be considered as candidate keys? Which field or fields is the best for primary key? Give reasons of your answer. 4. Write SQL DDL to do the following: (following the integer, varchar() data types as shown in the textbook) 4a. Create a table driver with the following fields: license, name, address. Select a primary key. 4b. Create a table car with the following fields: plate, model, year, color. Select a primary key. 4c. Create a table owner with the following fields: license, plate. Select a primary key. When everything works, copy and paste your SQL commands from the query to the word file with the answer of the first three questions. Submit the word file.