The control group in this experiment is the group of tomatoes that do not receive any fertilizers i.e. fourth tomato plants.
<h3>What is Fertilizer?</h3>
Fertilizer may be defined as any chemical or natural substance which is added to the soil with the intention of enhancing productivity.
All those groups of tomatoes in which fertilizers are added behave as a reference group while those in which fertilizer is not added behave as a control group.
Therefore, it is well described above.
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The correct option is D.
A natural law refers to a description of natural event that has been proved to be true without exception. Such a law usually generalizes a body of observation but can not explain why the observation occur. An example of a natural law is Newton's law of gravity, he observed that an object thrown up usually come down but can not explain the reason behind this observation.
Biotic refers to the living factors and abiotic refers to the nonliving factors.
A gene pool changes throughout evolution this could be natural selection, genetic drift or a mutation. A gene pool does this to adapt with the needs of the environment it is in