Explanation
The String.Join method takes two parameters: a separator and an array of strings. It returns a new string that concatenates the elements of the array using the separator. The correct syntax is String.Join(separator, array).
Therefore, option B is the correct answer.
References:
Automation Developer Associate Training course, Section 1: Data Manipulation, Lecture: Data Manipulation with Strings in Studio How to use Array of string forum post, Answer by @balupad14