What is the primary function of the Program Counter (PC) in a CPU?

Consider the following Python code:

class Vehicle:

    def __init__(self, brand):

        self.brand = brand

In a system using the Least Recently Used (LRU) page replacement algorithm, which of the following statements holds true? 

What is capacity of memory having 16 address lines of row decoder, 8 address lines for column decoder and 8 data lines? 

Consider the following Java code:

import java.util.regex.Matcher;

import java.util.regex.Pattern;

public class RegexGroup {

In public-private key encryption , which of the following is true regarding the private key ?

What is the primary purpose of virtual memory in an operating system? 

Average waiting time of all process?