13. which of the following represents replacement reproduction?
a. each couple has only two children
b. a couple has no children but each has two siblings
c. a government policy that limits the number of children per family
d. a couple with four children
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The answer is A. Each couple has only two children

Explanation:

The replacement reproductionis inferred to the minimum reproduction that a closed population needs so that it remains endlessly in time without decreasing its volume. This value is around 2.1 children on average. This is understood that a woman must reproduce herself and her partner, the decimal is because there are women who have no children.

answer: - few nutrients

high pressure

low temperatures

explanation: 1. few nutrients:   open-ocean zone is located way far from the land, which is the main source of the essential nutrients.2. high pressure: pressure increases by 1 atmosphere for every 10 meters increase in depth.3. ample sunlight: a large fraction of the sunlight is reflected back to the atmosphere from the sea surface. 4. varying salinity: below the thermocline, the water is isolated from the atmosphere so the salinity remains stable over the year.5. low temperatures:   the temperature of open-ocean zone ranges from a low of -2°c to an average of 17°c

answer by yourhope:

answer is

human impact on the environment can be seen in the deterioration of the !

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