Which tick does not transmit any diseases?

The Groundhog Tick, also known as Ixodes hexagonus, is not recognized as a significant vector for transmitting diseases to humans or domestic animals. This tick is primarily associated with woodlands and habitats frequented by groundhogs, and it does not feed on humans or pets as commonly as the other ticks mentioned.

On the other hand, the American Dog Tick, Blacklegged "Deer" Tick, and Lone Star Tick are known for their roles in transmitting various diseases. The American Dog Tick can transmit Rocky Mountain spotted fever and tularemia. The Blacklegged Tick is responsible for Lyme disease, and the Lone Star Tick can transmit diseases such as ehrlichiosis and the southern tick-associated rash illness (STARI). This differentiates the Groundhog Tick and solidifies its classification as a tick that does not transmit diseases, making it the correct answer in this context.