Under the periodic inventory system, the companies evaluate the COGS (Cost of goods sold) at the end of the accounting year or the fiscal period. And the details of the goods on hand which are not available, in this system.
And under the perpetual inventory system, this offer better control over the inventories rather than the periodic inventory system. And this system requires the COGS (Cost of goods sold) to be acknowledged at the time of sale and it contain the more accurate value of goods on hand.
Therefore, the statement which is correct is that the perpetual inventory system, offer better control over inventories.
A customer who sold a bond at a loss must wait how long before he can buy back a substantially identical bond and not have the sale classified as a wash sale? 30 days.