A developer has created a string array variable as shown below:UserNames = {"Jane", "Jack", "Jill",...

To print the elements of a string array separated by a specific string, the String.Join method is used in C#. This method takes two parameters: the first is the separator string and the second is the array to join into a single string.

Given the options and the requirement to separate array elements with a comma and a space (", "), the correct expression to use in a Log Message activity would be:

C. String.Join(", ", UserNames)

This will produce a single string with each element of the UserNames array separated by ", " (a comma followed by a space).