Analyze the following code:

```
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;

public class Test extends Application {
@Override // Override the start method in the Application class
public void start(Stage primaryStage) {
StackPane pane = new StackPane();
Button bt1 = new Button("Java");
Button bt2 = new Button("Java");
Button bt3 = new Button("Java");
Button bt4 = new Button("Java");
pane.getChildren().addAll(bt1, bt2, bt3, bt4);

Scene scene = new Scene(pane, 200, 250);
primaryStage.setTitle("Test"); // Set the stage title
primaryStage.setScene(scene); // Place the scene in the stage
primaryStage.show(); // Display the stage
}

/**
* The main method is only needed for the IDE with limited JavaFX
* support. Not needed for running from the command line.
*/
public static void main(String[] args) {
launch(args);
}
}
```
a. One button is displayed with the text "Java".
b. Two buttons are displayed with the same text "Java".
c. Three buttons are displayed with the same text "Java".
d. Four buttons are displayed with the same text "Java".

a. One button is displayed with the text "Java".
Because you are using a StackPane.