Answer :
The right option is; a. they are usually written in first person.
A diary is a daily record of personal experiences. A diary contains discrete records that are arranged by date stating what has occurred daily, or other period. A personal diary may contain personal experiences, feelings or thoughts while a journal is a daily record of activities, ideas or observations on any event or things. A journal may also contain personal experiences, feelings, or thoughts. In journals and diaries, the writer may write events from their perception using the first person such as "I".