Final answer:
Surface circulation is faster than thermohaline circulation due to differences in their characteristics.
Step-by-step explanation:
The comparison between the length of time required for completion of a circuit of surface circulation and that needed for thermohaline circulation can be explained by understanding their characteristics. Surface circulation refers to the movement of water in the upper layer of the ocean, driven primarily by wind and currents. Thermohaline circulation, on the other hand, involves deep ocean currents that are driven by differences in temperature and salinity.
In general, surface circulation is faster than thermohaline circulation. Surface currents can span large distances relatively quickly, often taking weeks or months to complete a circuit around the globe. In contrast, thermohaline circulation operates on a much slower timescale, typically taking hundreds or even thousands of years to complete a single circuit. This is because the movement of water in the deep ocean is much slower due to its greater depth and lower energy transfer.
Therefore, the correct answer to the question is b) Surface circulation is faster than thermohaline circulation.