Last year, Heidenescher Corporation's variable costing net operating income was $63,600 and its inventory decreased by 600 units. Fixed manufacturing...

Last year, Heidenescher Corporation's variable costing net operating income was $63,600 and its inventory decreased by 600 units. Fixed manufacturing overhead cost was $1 per unit. What was the absorption costing net operating income last year? a)$64,200 b)$63,00 c) $63,600 d)$600