To determine whether a string has specific sequence of characters, use . . . . . . . .

Contains method
Specific method
Sequence method
Check method

The correct answer is A. Contains method.

The Contains method is a string method that checks if a specified string is contained within the current string. The syntax for the Contains method is:

string.Contains(string)

where string is the string to be searched for.

For example, the following code checks if the string “hello” is contained in the string “world hello”:

if ("world hello".Contains("hello"))
{
Console.WriteLine("The string 'hello' is contained in the string 'world hello'.");
}

The output of the code is:

The string 'hello' is contained in the string 'world hello'.

The Contains method is a very useful method for checking if a string contains a specific sequence of characters. It is often used in conjunction with other string methods, such as the IndexOf method, to find the location of a specific sequence of characters within a string.

The other options are incorrect because they do not refer to a valid string method.