1.What is difference between constant, readonly and static variables?2.There are two arrays containing integers – Array1 and Array2. The size of Array1 is m, and Array2 is n. Both arrays are sorted in ascending order. Write a function (in any language of your choice) that will merge the two arrays into a third array which again has numbers arranged in ascending order. The function will accept two arrays as arguments and return the third, merged array?3.Write a function in C# to implement Trim function (removing spaces only from the beginning and end of a string), without using any string class function except length. If the input is “ Trim this String “, the output should be “Trim this String”.4.Suppose there is a function defined as:String Reverse (String inputString)As the name suggests, the function reverses the input string and returns the reversed string. If “abcd” is the inputString, the output will be “dcba”. What different values of the inputString will you use to ensure that the function is robust and handles all possible cases? In other words, list all the test cases for this function.