Question

exam lesson name: introduction to oceanography
exam number: 700793rr
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question 4 of 20 :
select the best answer for the question.

1. which of the following provides an accurate description of sea surface salinity along the equator?

○ a. sea surface salinity at the equator is low due to loss of freshwater via evaporation.
○ b. sea surface salinity at the equator is high due to loss of freshwater via evaporation.
○ c. sea surface salinity at the equator is high due to freshwater input via precipitation.
○ d. sea surface salinity at the equator is low due to freshwater input via precipitation.

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Explanation:

To determine the correct answer, we analyze the factors affecting sea - surface salinity at the equator. The equatorial region has a large amount of precipitation (freshwater input). An increase in freshwater input (from precipitation) dilutes the seawater, which leads to a decrease in sea - surface salinity.

• Option A: Evaporation removes water, which would increase salinity, not decrease it. And the equator has high precipitation, not mainly evaporation - driven low salinity for this reason. So A is incorrect.
• Option B: As mentioned, evaporation increases salinity, but the equator has high precipitation that counteracts this. Also, the equator's salinity is low, not high. So B is incorrect.
• Option C: Precipitation adds freshwater, which should decrease salinity, not increase it. So C is incorrect.
• Option D: The equator has abundant precipitation (freshwater input), and this freshwater dilutes the seawater, resulting in low sea - surface salinity. This option correctly explains the relationship between precipitation and sea - surface salinity at the equator.

Answer:

D. Sea surface salinity at the equator is low due to freshwater input via precipitation.