问题：

[单选]

Examine the data in the EMPLOYEES and EMP_HIST tables:
EMPLOYEES
NAME DEPT_ID MGR_ID JOB_ID SALARY
EMPLOYEE_ID
101 Smith 20 120 SA_REP 4000
102 Martin 10 105 CLERK 2500
103 Chris 20 120 IT_ADMIN 4200
104 John 30 108 HR_CLERK 2500
105 Diana 30 108 IT_ADMIN 5000
106 Smith 40 110 AD_ASST 3000
108 Jennifer 30 110 HR_DIR 6500
110 Bob 40 EX_DIR 8000
120 Ravi 20 110 SA_DIR 6500
EMP HIST
EMPLOYEE_ID NAME JOB_ID SALARY
101 Smith SA_CLERK 2000
103 Chris IT_CLERK 2200
104 John HR_CLERK 2000
106 Smith AD_ASST 3000
108 Jennifer HR_MGR 4500
The EMP_HIST table is updated at the end of every year. The employee ID, name, job ID, and salary of each existing employee are modified with the latest data. New employee details are added to the table.
Which statement accomplishes this task?（）

A . UPDATE emp_hist SET employee_id, name, job_id, salary = (SELECT employee_id, name, job_id, salary FROM employees) WHERE employee_id IN (SELECT employee_id FROM employees);
B . MERGE INTO emp_hist eh USING employees e ON (eh.employee_id = e.employee_id) WHEN MATCHED THEN UPDATE SET eh.name = e.name, eh.job_id = e.job_id, eh.salary = e.salary WHEN NOT MATCHED THEN INSERT VALUES (e.employee id, e.name, job id, e.salary);
C . MERGE INTO emp_hist eh USING employees e ON (eh.employee_id = e.employee_id) WHEN MATCHED THEN UPDATE emp hist SET eh.name = e.name, eh.job_id = e.job_id, eh.salary = e.salary WHEN NOT MATCHED THEN INSERT INTO emp_hist VALUES (e.employees_id, e.name, e.job_id, e.salary);
D . MERGE INTO emp_hist eh USING employees e WHEN MATCHED THEN UPDATE emp_hist SET eh.name = e.name, eh.job_id = e.job_id, eh.salary = e.salary WHEN NOT MATCHED THEN INSERT INTO emp_hist VALUES (e.employees_id, e.name, e.job_id, e.salary)