The correct answer is D) a single pressure stage with two or more velocity stages. The design characteristics of a velocity-compounded impulse turbine include the utilization of a single pressure stage, which extracts some of the steam's pressure, followed by two or more velocity stages that extract the remaining energy from the steam's velocity. This configuration allows the turbine to more efficiently convert the steam's energy into mechanical work compared to a simple impulse turbine with only one row of rotating blades. The other options are incorrect because they do not accurately describe the key design features of a velocity-compounded impulse turbine. Option A describes a simple impulse turbine, option B describes a low-velocity steam jet, and option C describes a multi-stage impulse turbine without the pressure stage.