Answer: C. II and III
Step-by-step explanation:
The customer ordered for 1,000 shares of a stock at $40 and so this is what the registered representative should give the customer. As such, if in the first place the order was possible to be done, then it will have to be done now and the registered representative's firm are obligated to provide the amount in question.
Any costs associated with filling the remaining 900 share order is the responsibility of the firm and not of the customer as they made the error not the customer.