The production group of Gray Manufacturing had 100 units as work in process at the beginning of the month. These units were 35% complete. It has 400 units which are 15% complete at the end of the month. During the month, it completed and transferred 600 units. Direct materials are added at the beginning of production. Conversion costs are allocated evenly throughout production. Gray Manufacturing uses the weighted-average process-costing method. What is the number of equivalent units of work done during the month with regards to direct materials?

A. 1100 units

B. 900 units

C. 700 units

D. 600 units