Given the code fragment:

Which two modifications enable the code to compile?

Given the code fragment:

Which code fragment, when inserted at line n1, enables the App class to print Equal?

You are developing a banking module. You have developed a class named ccMask that has a maskcc method.
Given the code fragment:

You must ensure that the maskcc method returns a string that hides all digits of the credit card number except the four last digits (and the hyphens that separate each group of four digits).
Which two code fragments should you use at line n1, independently, to achieve this requirement? (Choose two.)

Given the code fragment:

Which option can replace xxx to enable the code to print 135?

Given the definitions of the MyString class and the Test class:

What is the result?