Which statement is true about triggers on data definition language (DDL) statements?
A. They can be used to track changes only to a table or index.
B. They can be defined by all users in the database or only by a specific user.
C. They are fired only when the owner of the object Issues the DDL statement.
D. They can be used to track changes to a table, table space, view, or synonym.
Looks like D is correct.
B could has been correct, but it says about trigger definition, not about DDL statement issue by users:
https://docs.oracle.com/cd/B19306_01/server.102/b14220/triggers.htm
“You can write triggers that fire whenever one of the following operations occurs:
DDL statements (CREATE or ALTER primarily) issued either by a particular schema/user or by any schema/user in the database”