Soil horizons are defined by physical features. Please select the best answer from the choices provided
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A soil horizon is a layer parallel to the soil surface, whose physical characteristics differ from the layers above and beneath. ... Horizons are defined in most cases by obvious physical features, chiefly colour and texture.

Explanation:

•there must be variation for the particular trait within a population.

•the variation must be inheritable (that is, it must be capable of being passed on from the parents to their offspring).

•individuals with one version of the trait must produce more offspring than those with a different version of the trait.good

explanation:

answer: 20 percent

the fish culture has become a developing commercial practice in developing countries which is already prominent in developed countries of the world. the major fish protein demand is being supplemented in developing countries is   fishing to meet the needs of the growing population. therefore, in some developing nations, the percentage of animal protein from fish in the diet can be as high as 20 percent.