The following data have been collected for four different cost items Total Cost at Total Cost at Cost Items 140 Units 180 Units $ 11,200 $ 14,400 B $ 7,000 $ 8,100 C $ 6,500 $ 6,500 D $ 9,100 $ 11,700 Which of the following classifications of these cost items by cost behavior is correct? Cost A mixed Cost B variable Cost C fixed Cost D mixed Cost A variable Cost B fixed Cost C mixed Cost D variable Cost A variable Cost B mixed Cost C fixed Cost D variable Cost A mixed Cost B fixed Cost C variable Cost D mixed