Concord Company had the following department data on physical units:

$\backslash$table$[[$Work in process inventory, beginning,$4000],[$Completed and transferred out,$14000],[$Work in process inventory, ending,$2300]]$

Materials are added at the beginning of the process. What are the equivalent units of production for materials during the period?

$10000$

$18000$

$16300$

$15700$