问题：

[单选]

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 ='Smith' WHERE employee_id = 180;
C . UPDATE employees SET first_name = 'John' AND last_name ='Smith' WHERE employee_id = 180;
D . UPDATE employees SET first_name = 'John', last_name ='Smith' WHERE employee_id = 180