Which star lies over 3,000 light-years away and is found in the Cygnus constellation?

Deneb is indeed the correct choice as it is one of the most prominent stars in the constellation Cygnus and is located approximately 2,600 light-years from Earth, though some estimates suggest it may be even farther—over 3,000 light-years. Deneb is notable not only for its distance but also for its brightness; it is one of the brightest stars in the night sky and serves as a part of the Summer Triangle asterism.

The other stars listed do not fit the criteria as they are located much closer to Earth. Vega, found in the constellation Lyra, is about 25 light-years away; Pollux, in Gemini, is approximately 34 light-years distant; and Procyon, in Canis Minor, is roughly 11.5 light-years away. This makes Deneb the only star among the options that meets the requirement of being over 3,000 light-years away, specifically in the constellation of Cygnus.