In Branch-schema, {branchcustomer name} and {branch-name, branch-city} are both superkeys. {branch-name, branch-city} is not a candidate key, because {branch-name} is a subset of {branch-name, branchcity} and {branch-name} itself is a superkey.
Strong entity set. The primary key of the entity set becomes the primary key of the relation. Weak entity set. The table, and thus the relation, corresponding to a weak entity set includes