Which statement causes more undo generation?

Exhibit. Which statement causes more undo generation?

A.
SELECT * FROM emp;

B.
DELETE FROM emp WHERE empno=7934;

C.
UPDATE emp SET comm=400 WHERE empno=7844;

D.
INSERT INTO emp VALUES(7999,’JHON’,’CLERK’,7782,’10-MAY-83′,1500,NULL,10);

Explanation: