The zero volatility spread (Z-spread) is the spread that:（）

A. is added to the yield to maturity of a similar maturity Treasury bond to equal the yield to maturity of the risky bond.

B. is added to each spot rate on the Treasury yield curve that will cause the present value of the bond’s cash flows to equal its market price.

C. results when the cost of the call option in percent is subtracted from the option adjusted spread.

Virtualization is an approach to IT that pools and shares (71) so that utilization is optimized and supplies automatically meet demand. Traditional IT environments are often silos, where both technology and human (72) are aligned around an application or business function. With a virtualized (73) , people, processes, and technology are focused on meeting service levels, (74) is allocated dynamically, resources are optimized, and the entire infrastructure is simplified and flexible. We offer a broad spectrum of virtualization (75) that allows customers to choose the most appropriate path and optimization focus for their IT infrastructure resources.

（71）是（）

A.advantages

B.resources

C.benefits

D.precedents