A client is scheduled to undergo percutaneous transluminal coronary angioplasty (PTCA). The nurse explains the procedure to the client. Which of the following statements by the nurse is most appropriate

A. "PTCA involves opening a blocked artery with an inflatable balloon located on the end of a catheter. "
B. "PTCA involves cutting away blockages with a special catheter. "
C. "PTCA involves passing a catheter through the coronary arteries to find blocked arteries. "
D. "PTCA involves inserting grafts to divert blood from blocked coronary arteries. "

张某王某二人订立委托合同，张某委托王某设计商品外观，但合同中未明确该专利归属，则如果发生纠纷，该外观设计专利归( )。

A．张某所有

B．王某所有

C．张王共有

D．国家所有