2. Write a C+ program to calculate the area of a circle. (Area = r2, where is a constant with value 3.1416 and r is the radius taken as input from user during run-time) A. Defining an object macro for the constant T B. Define a function macro for finding the square of a number C. Use nested macro for defining the Area of the circle 2. Write a C+ program to calculate the area of a circle. (Area = r2, where is a constant with value 3.1416 and r is the radius taken as input from user during run-time) A. Defining an object macro for the constant T B. Define a function macro for finding the square of a number C. Use nested macro for defining the Area of the circle