The cost of an asset is $20,000. The expected production over the life of the asset is 500,000 units. The actual production is as follows: Year 1 60,000 units Year 2 40,000 units Year 3 30,000 units Year 4 25,000 units The company uses the production method for estimating depreciation expense. What is the depreciation expense to be accounted for year 2? a. $1,600 b. $2,000 C. $4,000 d. $5,200