D. They could pay soldiers for their service with land rather than money.
Explanation:
The pillage and gift system consisted in the pillaging of conquered lands, and the gift of those lands to the soldiers who helped conquered them in first place.
As the functioning of the system implies, it was used by nobles to pay their soldiers with land instead of currency, since payments in currency form were not always convenient or possible because some nobles could not issue currency, or could do so, but at the cost of debasement and inflation.
True, post WW2 Japans economy boomed and especially in that time they became a world economic power and today they are still one of the strongest economies in Asia.
