Answer:C. It makes it more difficult for the company to define an appropriate time period.
Explanation: Obsolete Items or products are products are no longer useful or relevant,it can be used to describe a product whose Quality has adversely depleted making it not useful.
With the information,since the products are fast becoming Obsolete than when compared to 10years ago,it makes it more difficult to determine or arrive at the appropriate time period for the company to keep the product before it becomes obsolete.