View in a database system are important because:
1. They improve the efficiency of query execution.
2. They help provide data independence.
3. They allow the schema to change without forcing existing applications to be recompiled.
4. They help with access control by allowing users to see only a particular subset of the data in database.
(a) 2 and 4 (b) 1 and 4
(c) 1 and 3 (d) 2 and 3