Deuterium Is Much More Abundant on Venus Than Earth

Deuterium is much more abundant on Venus than Earth.What do we think this fact tells us about Venus?

A) that it once had a much stronger magnetic field than it does today
B) that the greenhouse effect on Venus must have been much weaker in the distant past
C) that it has lost a tremendous amount of water as a result of molecules being split by ultraviolet light and the hydrogen escaping to space
D) that volcanoes on Venus did not outgas as much water as volcanoes on Earth