Add evidence of manually controlled tower.
To track which tower is currently selected in the game, add private static attribute-controlledInstance to the ManualTower class and initialize it to null. Static attribute is related to the whole class, not to an object of a class.Hence, defining a static variable will allow us to determinewhether tower has been selected and, if so, which one, byreferencing  theclass name, without needing to access aspecific object. The teacher should emphasize that there is one controlledInstancefor the whole game. At the beginning, controlledInstance should be initialized to null, as there is no selected tower. Inspect the internal state of class. Here the teacher explains differences between static and non-static attributes. The teacher with studentsdiscussbenefits of using static attributes in games. Teacher should also mention here static methods and discuss with the students where usingstatic methods is beneficial.