(a) What is the difference between call by reference and call by value? Discuss the different ways in which functions can modify variables in the environment in which they are called. [4 marks] (b) Write a short C program that demonstrates: i) An example of a function that uses calling by value. Create a main that declares and initializes two floats of your choice, and passes them into the function which returns the product of the two. Save your program to the file: lastName_firstName_EEEE1042Final_3bi.c and submit it together with your exam. For full marks you must adequately comment your code. [5 marks] ii) An example of a function that uses calling by reference. Create a main that declares and initializes two floats and passes them into the function that exchanges their values. Save your program to the file: lastName_firstName_EEEE1042Final_3bii.c and submit it together with your exam. For full marks you must adequately comment your code. [5 marks] iii) Repeat b)ii above, but now swapping two strings (char-arrays) "First string" and "Second string" rather than two floats. Save your program to the file: lastName_firstName_EEEE1042Final_3biii.c and submit it together with your exam. For full marks you must adequately comment your code. [6 marks]