Answer:
D. They could pay soldiers for their service with land rather than money.
Step-by-step 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.