DNA structure. DNA is made up of molecules called nucleotides. Each nucleotide contains a phosphate group, a sugar group and a nitrogen base. The four types of nitrogen bases are adenine (A), thymine (T), guanine (G) and cytosine (C).
The answer is A. Pollution is harmful substances that can damage organisms and the environment. Decomposition returns nutrients into the soil which helps organisms grow and reproduce. Replenishment is to fill something which would be a good thing. Improvement means to make something better which is also a good thing. Degradation means to degrade or make something worse which is what pollution is doing to organisms and the environment.
The answer is : It is a set of hypotheses supported by scientific findings. This explains why evolution is classified as a theory. Evolution<span> is a scientific theory. In science, a theory is the most logical explanation for how a natural phenomenon works.</span>