What buttons are used to navigate the SMDT?

The correct answer is "Puck and scroll" because this terminology specifically refers to the navigation method used on the SMDT, or Standard Mobile Data Terminal, which is commonly utilized by bus operators. The "puck" refers to a joystick or control that allows operators to move through options on the screen smoothly, while the "scroll" function lets them navigate through lists or selection menus.

This method is essential for bus operators to access necessary information quickly and efficiently while on the move, enabling them to focus on their driving responsibilities while still managing required data inputs. The other options refer to different navigation styles that are not specifically applicable to the SMDT, making them unsuitable for the context of the question.