A. SELECT last_name, hire_date, salary
FROM employees
WHERE manager_id = (SELECT employee_id FROM employees WHERE employee_id = 100) UNION ALL (SELECT last_name, hire_date, salary FROM employees WHERE hire_date > SYSDATE -180 INTERSECT SELECT last_name, hire_date, salary FROM employees WHERE salary > 10000);

B. SELECT last_name, hire_date, salary
FROM employees
WHERE salary > 10000
UNION ALL
SELECT last_name, hire_date, salary
FROM employees
WHERE manager_ID = (SELECT employee_id FROM employees WHERE employee_id = 100) INTERSECT SELECT last_name, hire_date, salary FROM employees WHERE hire_date > SYSDATE- 180;

C. (SELECT last_name, hire_date, salary
FROM employees
WHERE salary > 10000
UNION ALL
SELECT last_name, hire_date, salary
FROM employees
WHERE manager_ID = (SELECT employee_id FROM employees WHERE employee_id = 100)) UNION SELECT last_name, hire_date, salary FROM employees WHERE hire_date > SYSDATE -180;

D. SELECT last_name, hire_date, salary
FROM employees
WHERE manager_id = (SELECT employee_id FROM employees WHERE employee_id = '100') UNION SELECT last_name, hire_date, salary FROM employees WHERE hire_date > SYSDATE -180 INTERSECT SELECT last_name, hire_date, salary FROM employees WHERE salary > 10000;