Final answer:
Without specific data on the units at the beginning, introduced, and remaining at the end of the period, it's not possible to calculate the number of units started and completed in the forming department; hence, the answer is not determinable.
Step-by-step explanation:
In order to calculate the number of units started and completed in a period for the forming department, we would typically need additional information such as the number of units at the beginning, the number of units introduced during the period, and the number of units at the end of the period. Without this information, no calculation can be made, thus making it impossible to determine whether the units completed are less than, equal to, or more than the units started. Consequently, the correct answer to the question as it stands would be D) Not determinable.