My diagram from the conditions is as follows (I hope it's understandable):
hr/R hr hr/R R R/hr
O N P L J
1. 2. 3. 4. 5.
O,N,P, L and J are locked in due to the conditions presented in the stimulus and question. HR must be in 2 and R in 4 but I thought HR or R could be in spots 1,3, and 5? What is the limitation on Jackson so than it can receive only rain? Thus eliminating choice D.