Mars Odyssey Was Unsuccessful in Detecting Evidence of Large Bodies

Mars Odyssey was unsuccessful in detecting evidence of large bodies of frozen water well below the Martian surface. This is not surprising because:

A) the neutrons it was detecting can only escape from the top meter or so of the ground.
B) volcanic activity suggests it is too hot below the surface for frozen water to exist.
C) the lack of tectonic activity suggests that the crust of Mars is very solid with no possibility of water penetration in the past.
D) the spectral signature of H₂O, which Mars Odyssey was detecting, can only escape from the top few centimeters of the soil.