The Player class uses static (class) properties called scoreCorrect and scoreIncorrect to store the current total number of correct and incorrect guesses, respectively. Since these are public static properties, any object from any scene can access (set or get) these values, since the static properties are remembered from scene to scene. This class also provides the public static method called ZeroTotals(), which resets both values to zero.
When the scene0_mainMenu scene is loaded, all the GameObjects with scripts will have their Start() methods executed. The UI Text GameObject called Text-score has an instance of the UpdateScoreText class as a script component so that the script's Start() method will be executed, which retrieves the correct and incorrect totals from the Player class, creates a scoreMessage string about the current score, and updates the...