Question: A Super keys for which no proper subset is a super key. Such a minimal Super keys are called _______

Answer:

It is possible that several distinct sets of attributes could serve as a candidate key. Suppose that a combination of customer-name and customer-street is sufficient to distinguish among members of the customer entity set. Then, both {customer-id} and {customer-name, customer-street} are candidate keys. Although the attributes customer-id and customer-name together can distinguish customer entities, their combination does not form a candidate key, since the attribute customer-id alone is a candidate key