Which of the Following Correctly Describes the Rate of Inventory

Which of the following correctly describes the rate of inventory turnover?

A) It is how rapidly inventory is sold.
B) It is how many days it takes the inventory to travel between the seller's warehouse and the buyer's warehouse.
C) It is how quickly inventory is received from the supplier after the order is placed.
D) It is how many days it takes from the time an order is received to the day it is shipped.