I need help of these questions

10. Sid Inc. has an item in its inventory, with the following information as at years ended December 31,2015 and December 31,2016 , respectively: Regarding the adjusting entry that Sid should record on December 31, 2015, and/or the adjusting entry that Sid should record on December 31, 2016, which of the following statements is true? a) Sid should record a $1,000 debit to cost of sales on December 31,2015 , and a $1,000 credit to cost of sales on December 31,2016. b) Sid should record a $1,000 debit to cost of sales on December 31,2015 , and a $650 credit to cost of sales on December 31,2016. c) Sid should record a $1,000 debit to cost of sales on December 31,2015 , and no adjusting entry on December 31,2016. d) Sid should not record any adjusting entry on December 31, 2015, or on December 31 , 2016 , because estimated sale price per unit is greater than cost per unit on both dates. e) Sid should not record any adjusting entry on December 31,2015 , or on December 31 , 2016 , because estimated sale price per unit less estimated selling cost per unit, increases to an amount greater than cost per unit by December 31,2016. 11. The accounting concept that best supports your response in question 4 is: a. Cost principle. b. Matching principle. c. Prudence. d. Revenue recognition principle. e. Understandability