The open ocean, sea floor, and coral reefs are all examples of habitats with high rates of primary production.

As the open ocean, sea floor, and coral reefs are the habitats where the plants are present in very much quantity because they can easily get their food from water, sunlight that is a source from the sun and the water is the source from open ocean. when the plants get more nourishment in this habitat, these habitat becomes the high rate primary production habitat. as the sunlight increases, the pigment known as chlorophyll also increases. This is the reason open ocean, sea floor, and coral reefs are all examples of habitats with high rates of primary production.

less than one you can't create energy

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.