Bing Manufacturing Uses a Weighted-Average Process-Costing System

Bing Manufacturing uses a weighted-average process-costing system. All materials are introduced at the start of manufacturing, and conversion costs are incurred evenly throughout the process. The company's beginning and ending work-in-process inventories totaled 30,000 units and 35,000 units, respectively, with the latter units being 40% complete at the end of the period. Bing started 30,000 units into production and completed 25,000 units. Manufacturing costs were as follows: Beginning work in process: Materials, $100,000; conversion cost, $200,000
Current work in process: Materials, $160,000; conversion cost, $450,000.
Bing's equivalent-unit cost for materials is:

A) $2.67.
B) $4.00.
C) $4.33.
D) $7.20
E) $10.40.