To project the dorsum sella within the formen magnum in a skull of average shape.the orbito –meatal line is placed perpendicular to the film and the central ray angled cranially

To project the dorsum sella within the formen magnum in a skull of average shape.the orbito –meatal line is placed perpendicular to the film and the central ray angled cranially:
a- 5 degrees
b- 15 degrees
c- 25 degrees
d- 60 degrees