Explanation:
Online data files should be synchronized in order for a database to start. Incorrect Answer:
1: It’s not required that temp files should be synchronized for database to start.
3: Offline data files don’t need to be synchronized.
4: Read only data files don’t need to be synchronized.
Reference:
OCP Oracle 9i Database: Fundamentals II Exam Guide, Rama Velpuri, p. 174-175
Chapter 7: Instance and Media Recovery Structures

---