Why Did the Terrestrial Planets Lose the Majority of the Gases

Why did the terrestrial planets lose the majority of the gases in their primary atmospheres?

A) They were too hot and their escape velocities too low to hold onto them.
B) The solar wind was too strong and destroyed the planets' magnetospheres.
C) Their high surface temperatures made the gas chemically react with the rock.
D) The initial gases were so heavy when the planet differentiated that they sank to the core.
E) There wasn't much gas to begin with.