Nadina is struggling to decide whether to buy a new sweater that she really cannot afford. what role would each f the three parts of her personality (as theorized by freud) pay in her decision

When deciding whether or not she should buy an expensive sweater, Nadina's id, ego and superego would play a role. These three components of Nadina's personality would respectively play a role as follows:

i) Id- This component of personality is basically known as the pleasure seeking component, without any rationality, logical and regard for consequences. In Nadina's instance her id would play a role in urging her to give into her desire for pleasure and buy the expensive sweater. 

ii) Ego- The ego is a part of personality, that serves as a mediator between the pleasure-seeking and irrational id, and practical, real world aspects. The ego is characterized by reasoning and consideration of real-life, pragmatic aspects in the decision making process. Here, Nadina's ego would push her to think of a way to buy the sweater and devise a plan so that this purchase will not set back her finances greatly. For instance, Nadina might decide that if she buys the sweater, she can make up for it and justify the expense by fewer meals out for the next two weeks. 

iii) Superego- This aspect of personality includes our morals, beliefs and values which we imbibe from our parents, teachers and other authority figures in society. When making decisions, we take these morals and beliefs into consideration. In Nadina's case, her superego would urge her not to buy the sweater since she cannot afford it and probably needs to spend her money mostly on essentials instead (food, rent, education, children, etc.)

3. i would say one, but one is not prime nor composite.