Question

where is surface salinity generally highest? near the poles at the equator in sub - tropical regions it is the same everywhere

Explanation:

Surface salinity is influenced by evaporation, precipitation, and ocean circulation. Sub - tropical regions have high evaporation rates (due to warm temperatures and stable atmospheric conditions) and relatively low precipitation compared to the equator (where heavy rainfall dilutes salinity) and the poles (where cold temperatures mean low evaporation and often freshwater input from ice melt). So surface salinity is generally highest in sub - tropical regions.

Answer:

C. in sub - tropical regions