Quiz Question : What is used to let a class know about a data type you want to use?

Ritu, sorry, but I don't understand your question? I'll make a few guesses, but set me straight if I miss the target. Also, it's a good idea to ask the question using the Ask button, because that will put a link here that people answering your question can use to navigate to the challenge you're talking about. Without the name of the course, or a link to the challenge, all I know is that it is related to java.

You usually use data types when you create variables in classes:

int x = 0;
String s = "Hello, World!"
Date d = new Date();

Here the data types are int, String and Date.

You use data types when you give a method a non-void return type, and when you add formal parameters for your methods:

public double getArea(double width, double height) {
    return width * height;
}

Here the data types are double, double and double.

You use data types in programs when you are creating objects:

Scanner stdin = new Scanner(System.in);
Random r = new Random();
String s = new String("Hello, World!");
List<String> colors = new ArrayList<String>();

Here the data types are Scanner, Random, String and ArrayList<>, and the object stdin, r, s and colors.

If this totally misses the point let me know what the challenge question was.

An import statement