Zone of proximal development is the state of child development in physiological and learning manner.It develops cognitive skills,emotional process and psychological functions. These skills define difference between the activities that can be learned without guidance and skills that can be learned through teaching and guidance.
According to the question, infant would be able to do the block stacking on his own through zone of proximal development without the guidance of Ether as psychological process will develop in infant.
Use of power / authority is very common at work space. Compelling subordinate to do a task out of their job description and firing them in case they fail to do so is use of power. Same is mentioned in the question statement that Marietta's boss may fire her for not doing something which is not in the job description.
