Answer:
Alvin is propelled by _gas or diesel___ hydraulic thrusters and features an electrical system powered by lead-acid batteries.
Step-by-step explanation:
Technically, this implies that Alvin is working on motor-assist mode, using a hybrid engine. Alvin is, therefore, propelled by an internal combustion engine (given the presence of hydraulic thrusters) in addition to an electric motor, which uses energy stored in (lead-acid) batteries. Alvin must be a robot.