Auto DOP is enabled for your instance.
You execute the following statements: 
Which three are true about the execution of the join?
A.
Dictionary DOP is used to calculate statements DOP.
B.
Hinted DOP is used to calculate statement DOP.
C.
The EMPLOYEES table is accessed in parallel.
D.
The DEPARTMENTS table is accessed in parallel.
E.
The hint operates at the level of each table accessed by the statement.
Explanation:
C: As per ALTER TABLE employees PARALLEL 2;
Incorrect:
not D: As per ALTER TABLE departments NOPARALLEL;
B, C, D – correct
Lets perform the question and see that both tables scanned in Parallel (PX BLOCK ITERATOR in the execution plan) and look at note: DOP is 3 because of hint
murik@ORCL2> alter table employees parallel 2;
Таблица изменена.
murik@ORCL2> alter table departments noparallel;
Таблица изменена.
murik@ORCL2> set autotrace traceonly explain;
murik@ORCL2> SELECT /*+ PARALLEL(3)*/
2 e.last_name,d.department_name
3 FROM employees e ,departments d
4 WHERE e.department_id = d.department_id;
План выполнения
———————————————————-
Plan hash value: 2622561563
——————————————————————————————————————–
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | TQ |IN-OUT| PQ Distrib |
——————————————————————————————————————–
| 0 | SELECT STATEMENT | | 106 | 2862 | 5 (20)| 00:00:01 | | | |
| 1 | PX COORDINATOR | | | | | | | | |
| 2 | PX SEND QC (RANDOM) | :TQ10001 | 106 | 2862 | 5 (20)| 00:00:01 | Q1,01 | P->S | QC (RAND) |
|* 3 | HASH JOIN | | 106 | 2862 | 5 (20)| 00:00:01 | Q1,01 | PCWP | |
| 4 | PX RECEIVE | | 26 | 416 | 2 (0)| 00:00:01 | Q1,01 | PCWP | |
| 5 | PX SEND BROADCAST | :TQ10000 | 26 | 416 | 2 (0)| 00:00:01 | Q1,00 | P->P | BROADCAST |
| 6 | PX BLOCK ITERATOR | | 26 | 416 | 2 (0)| 00:00:01 | Q1,00 | PCWC | |
| 7 | TABLE ACCESS FULL| DEPARTMENTS | 26 | 416 | 2 (0)| 00:00:01 | Q1,00 | PCWP | |
| 8 | PX BLOCK ITERATOR | | 107 | 1177 | 2 (0)| 00:00:01 | Q1,01 | PCWC | |
| 9 | TABLE ACCESS FULL | EMPLOYEES | 107 | 1177 | 2 (0)| 00:00:01 | Q1,01 | PCWP | |
——————————————————————————————————————–
Predicate Information (identified by operation id):
—————————————————
3 – access(“E”.”DEPARTMENT_ID”=”D”.”DEPARTMENT_ID”)
Note
—–
– Degree of Parallelism is 3 because of hint
Agree with vasya