Examine the structure of the EMPLOYEES table:<br /> EMPLOYEE_ID NUMBER Primary Key<br /> FIRST_NAME VARCHAR2 (25)<br /> LAST_NAME VARCHAR2 (25)<br /> HIRE_DATE DATE<br /> 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;