Answer:
D. The order quantity is constant, regardless of the demand.
Explanation:
Basic Continuous Review Model relates to inventory stock management, where each time an inventory unit is added in or moved out the stock level is calculated again.
It do not assume that the order quantity is constant as it calculates inventory level after each order, there is no basic assumption as such.
The review model keeps on moving the stock and tries to maintain such level as by ordering the quantity sold, and it keeps on rotating, but there is no standard set for order quantity.