Final answer:
Magnetohydrodynamic drives function better in ocean water due to its higher electrical conductivity which decreases resistance. Superconducting magnets are ideal because they have zero resistance, thus eliminating energy losses and allowing for stronger magnetic fields.
Step-by-step explanation:
A magnetohydrodynamic (MHD) drive works by applying a magnetic force to a fluid that is electrically conductive, which propels the fluid without any moving mechanical parts. This functionality is particularly relevant in propulsion systems for submarines or ships. Ocean water has a higher salinity compared to fresh water and thus, a greater electrical conductivity, which is essential for the MHD process as it reduces electrical resistance and increases efficiency.
Regarding magnet choice, superconducting magnets are highly desirable in such systems because they can carry electric currents without any resistance, leading to zero energy loss in the form of heat, which makes them incredibly efficient. Additionally, superconducting magnets can create significantly stronger magnetic fields than ordinary magnets, which can effectively increase the force and thrust of the MHD drive.
Therefore, the correct answer to the question is: a) Ocean water has higher electrical conductivity, reducing resistance for the MHD drive. Superconducting magnets have zero resistance, eliminating energy losses. This suits the operation of MHD drives and explains the superior performance in ocean water and the appeal of using superconducting magnets.