Which of the Following Does Not Correctly Describe the Concept

Which of the following does not correctly describe the concept of net realizable value (NRV) ?

A) Estimates of NRV are based on the best evidence available at and shortly after the balance sheet date.
B) NRV generally does not change over time
C) NRV generally changes over time
D) A new estimate of NRV is required at each balance sheet date.