The answer is B but I am not sure how to get $$20,000.$ Here is the question:

$7.$ MPS Inc. reported the following data:

December $20$X$220$X$1$

Building $($net$)$ $$890,000$ $$920,000$

Proceeds from sale of building $420,000$

Gain on sale of building $20,000$

Cost of building purchased

during the year $390,000$

What amount of depreciation was recorded for the year ended December $31,20$X$1?$

A$.$ $$10,000$

B$.$ $$20,000$

C$.$ $$30,000$

D$.$ $$40,000$