Natural variation provided the phenotypes that natural selection then acted on, over time causing evolution
The answer is, Pericardium.
Gradual changes in the frequency of diseases over long periods are known as SECULAR TIME TRENDS. For example, the rate of mortality in USA due to coronary heart diseases over a period of time. Onset of puberty in girls is also a secular time trend.
Secular time trend is also referred as Secular Variation and Secular Drift.
Explanation:
Naturalists began to focus on the variability of species; the emergence of paleontology with the concept of extinction further undermined static views of nature. In the early 19th century Jean-Baptiste Lamarck (1744–1829) proposed his theory of the transmutation of species, the first fully formed theory of evolution.
In classical Latin, though, evolution had first denoted the unrolling of a scroll, and by the early 17th century, the English word evolution was often applied to 'the process of unrolling, opening out, or revealing'. It is this aspect of its application which may have been behind Darwin's reluctance to use the term.
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Answer:
D/ Kilograms per cubic-centimeter
