What is the term for a signal located at a fixed point that impacts a train's movement?

The correct choice is the term "Fixed Signal." A fixed signal is a signal that remains in a stationary position to convey information to train operators regarding the movement and safety protocols on a track section. These signals are vital for controlling train traffic and ensuring safe operation on the railway system, as they provide clear and consistent indications that do not change location.

In contrast, the other terms like mobile signal, dynamic signal, and adjustable signal typically refer to systems or signals that may change based on various conditions, movements, or operational needs rather than being stationary. Therefore, a fixed signal is specifically designed for its position and role in controlling train movements in a reliable way, which is crucial for safe and efficient rail transport.