In Cassette 12

In Cassette 12.3 (Retread Tires) , J.Lock stole money by selling the company's new tires and replacing them with retread tires.The key weakness in the control system failed to prevent or detect this scheme to continue was that

A) Lock often prepared purchase orders.
B) Lock was the chief accountant.
C) The president of the company signed cheques without reviewing any supporting documentation.
D) No one noticed the invoices for the retread tires.