Derive a class CombinedDiscount from DiscountPolicy, as described in Exercise 10. It should have a constructor that has two parameters of type DiscountPolicy. It should define the method computeDiscount to return the maximum value returned by computeDiscount for each of its two private discount policies. The two discount policies are described in Exercises 11 and 12.

Which of the following computing techniques will limit the vulnerability of a system to infection by a virus? (Select TWO).

A. Install a NAT firewall on the network B. Run an online malware scan monthly C. Only open email from recognized senders D. Update antivirus signatures on a daily basis E. Automatically update the operating system

The ____________ is useful in applications that must open an existing file because it allows the user to browse the system and select the file.

a. File Open Text method b. Open File Dialog control c. Open dialog box d. Windows Explorer