whenexamining a patient whose elbow is in partial flexion how should the AP projection be obtained

whenexamining a patient whose elbow is in partial flexion how should the AP projection be obtained?
1- with humerus parallel to film central ray perpendicular
2- with forearm parallel to film central ray perpendicular
3- through the partially flexed elbow resting on the olecranon process central ray perpendicular?
a. 1 only
b.1 and  2 only
c.2 and 3 only
d. 1,2 and 3