Options:
A. windward and leeward
B. east and west
C. north and south
D. port and starboard
The answer is option A "windward and leeward." Sand dunes are formed by wind blowing sand on-top of obstacles and they grow bigger and bigger in till it forms a hill made of sand which is a dune. The answer is option A because on a hill windward is towards the wind and leeward is behind or behind the hill.
Hope this helps.