Exercício: How Much

Could I help you, sir?’ ‘Would you be so kind as to tell me how much ?’
(A) does this CD player cost
(B) this CD player costs
(C) cost this CD player
(D) is the cost of this CD player
(E) cost is the CD player

resposta: B
Gostaria de saber pq não posso usar "How Much Does this CD player cost ?"