19.3.1 Use Collections of Records In this exercise, you will learn more about collections of records. Answer the following questions: | a) | Modify the script used earlier in this lab. Instead of using index-by table, use nested table. | | b) | Modify the script used earlier in this lab. Instead of using index-by table, use a varray. | | c) | Modify the script used earlier in this lab. Instead of using a cursor-based record, use a user -defined record. The new record should have three fields: first_name , last_name , enrollments . The last field will contain total number of courses in which a student is currently enrolled. | |