Alpha Sold Machinery That It Used in Its Business to Beta

Alpha sold machinery that it used in its business to Beta, a related entity, for $40,050. Beta used the machinery in its business. Alpha bought the machinery a few years ago for $49,950 and has claimed $30,050 of depreciation expense. What is the amount and character of Alpha's gain?

A) $20,150 ordinary income under §1239.
B) $10,000 ordinary gain and $10,150 §1231 gain.
C) $20,150 §1231 gain.
D) $20,150 capital gain.
E) None of the choices are correct.