Address-schema = (street_number, street_name, city, state, zip)

Enumerate all of the possible candidate keys for the Address schema under the following assumptions:

a. A state cannot have two cities with the same name.

b. Given the zip, you can uniquely identify the city and the state.

c. No physical city will have two addresses with the same street_number and street_name combination. Note, however, that two cities with the same name may have two such addresses.

d. No state will have two cities with the same name.

e. Given the street_number, street_name, city, and state, you can determine a unique zip code.

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I think the candidate key will be (zip) since it is only one that uniquely distinguishes out of all the schema.

Am I wrong? or Can you explain other possible candidate keys?