Note that mailing address is unique, but houses are not, meaning that you can't have house A and house B both referencing the same address.
So, in order to have a valid function, any two points on the function cannot have the same x value that lands on different y.
With this property mentioned, it's clear to see that
(house, address) is NOT a function; however, (address, house) is a function, since same x lands on multiple y values is a valid onto function. (a house that have multiple addresses)
ANSWER : C
I KNOW CAUSE IVE TOOKEN THE TEST
Answer:
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