Examine the structure of the EMPLOYEES table: EMPLOYEE_ID NUMBER Primary Key FIRST_NAME VARCHAR2 (25) LAST_NAME VARCHAR2 (25) HIRE_DATE DATE Which UPDATE statement is valid?（）

• A、UPDATE employees SET first_name = 'John' SET last_name = 'Smith' WHERE employee_id = 180;
• B、UPDATE employees SET first_name = 'John', SET last_name = 'Smoth' WHERE employee_id = 180;
• C、UPDATE employee SET first_name = 'John' AND last_name = 'Smith' WHERE employee_id = 180;
• D、UPDATE employee SET first_name = 'John', last_name = 'Smith' WHERE employee_id = 180;