What is the amount of Direct Materials Used? Work in

What is the amount of Direct Materials Used?
Work in Process, Beginning ..... $10,000
Work in Process, Ending ...... $15,000
Direct Labor costs incurred ..... $4,000
Cost of Goods Manufactured ..... $8,000
Factory Overhead .......... $8,000
a. $1,000
b. $4,000
c. $7,000
d. $3,000