during intravenous (IV) urography the prone position is generally recommended to demonstrate

during intravenous (IV) urography the prone position is generally recommended to demonstrate:
1-filling of obstructed ureters
2- the renal pelvis
3- the superior calyces
a. one only
a. 1 and 2 only
b. 1 and 3 only
c. 1,2 and 3