Question: What method correctly extends the string class?

1. public static string IsvalidName(this string i, string value) {}
2. public static void IsvalidName(this string i, string value) {}
3. public string IsvalidName(this string i, string value) {}
4. public void IsvalidName(this string i, string value) {}

Answer: The correct answer of the above question is Option A:public static string IsvalidName(this string i, string value) {}