Which of the following could serve as proof of residency in Utah?

A recent utility bill is a valid form of proof of residency in Utah because it typically includes the individual's name and current address, demonstrating where they live. Utility bills are considered reliable documents as they reflect an ongoing service and are regularly sent to residents, making them an accepted form of verification by state agencies.

In contrast, a letter from the IRS is not primarily intended to serve as residency proof, as it may lack a current address or the immediate association with residency that utility bills provide. An expired lease agreement is also not viable, as it does not reflect current residency and may not accurately indicate where someone lives anymore. Lastly, while a Social Security card is an important identification document, it does not provide address information, thus failing to serve as proof of residency.