Determine the value of stock as at 31st December

Given:

Sales #180,000
Stock 1/1 # 25,000
Purchases #110,000
Sales returns # 1000
Purchases returns # 1,500
Gross profit # 58,000

Determine the value of stock as at 31st December

A #8000

B #9,500

C #12,500

D #15,500

Answer is C