a) Mass balance
b) Energy balance
c) Time
d) Mass balance, energy balance and time

Answer: d
Explanation: Mass balances are fundamental to control the processing, particularly in the control of yields of the product. Energy balance is used in examination of each and every stage of a process, even extending over the total food production system from the farm to fork. The time unit is considered in continuous process in three periods. They are startup, continuous processing and close down.