1. Explain the role of the three macros and the va_list data type that feature in the definition of a function using a variable number of arguments. 2. Instead of designing a function that accepts a...

1. Explain the role of the three macros and the va_list data type that feature in the definition of a function using a variable number of arguments.

2. Instead of designing a function that accepts a variable number of integers as arguments, can we not use an array and pass its name and size to a function?

3. Write a program that uses a defined constant to (i) declare an int array, (ii) populate the array with scanf, (iii) print the last two array elements. The program must work with any array size by changing only the value of the defined constant.