Where does the PTO primarily place a trademark mark?

The correct answer is the Official Gazette. The United States Patent and Trademark Office (PTO) publishes the Official Gazette weekly as a means to inform the public about newly granted trademarks, notices of trademark opposition, and other related legal proceedings. This publication serves as an important tool for transparency, allowing third parties to be aware of new trademark registrations and to potentially challenge them if they believe their own trademark rights may be affected.

The other options do not serve the primary function reflected in the question. The Trademark Journal is not an official term commonly used within the PTO's framework. The Application Registry is more of an internal PTO record-keeping tool rather than a public-facing document. The Principal Register refers specifically to the primary trademark registry maintained by the PTO for trademarks that have been officially registered, but it is not the primary place where trademarks are announced or recorded for public awareness.