The state agency that collects taxes is:

The Utah State Tax Commission is the correct answer because it is the designated state agency responsible for the administration and collection of various taxes within Utah. This includes income tax, sales tax, property tax, and other tax-related functions. The Tax Commission oversees the enforcement of tax laws, ensures compliance, and facilitates taxpayers' understanding of their obligations.

In contrast, the IRS (Internal Revenue Service) is a federal agency that handles tax collection and enforcement at the national level, but it does not operate at the state level or collect state taxes. The Department of Justice primarily focuses on enforcing federal laws and ensuring justice, while the Department of Treasury manages national finances and issues currency, rather than dealing specifically with state tax collection. Hence, the Utah State Tax Commission's role is vital and specific to state tax administration, making it the accurate choice for this question.