多选题 以下是员工(EMPLOYEE)表的结构：

EMPLOYEE
EMPLOYEE_ID	NUMBER	NOT NULL, Primary Key
EMP_LNAME	VARCHAR2(25)
EMP_FNAME	VARCHAR2(25)
DEPT_ID	NUMBER	Foreign key to DEPT ID column of the DEPARTMENT table
JOB_ID	NUMBER	Foreign key to JOB ID column of the JOB table
MGR_ID	NUMBER	References EMPLOYEE ID column
SALARY	NUMBER(9, 2)
HIRE_DATE	DATE
DOB	DATE

请问，使用如下的哪个DDL语句可为EMP_LNAME列创建一个索引?
A．CREATE INDEX employee(emp_lname);
B．CREATE INDEX employee(emp_lname) employee_emp_lname_idx;
C．CREATE INDEX employee_emp_lname_idx
ON employee；
D．CREATE INDEX employeeemp_lname_idx
ON employee(emp_lname);