The answer is D. A is obviously incorrect because they just listed these many different cells that are grouped together. B is incorrect because not only similar cells are grouped together, and they often perform different functions. C is incorrect because the functions are never unrelated, they are usually interdependent with each other.
<span>The troposphere is the lowest portion of Earth's atmosphere. It contains approximately 75% of the atmosphere's mass and 99% of its water vapour and aerosols. The average depth of the troposphere is approximately 17 km in the middle latitudes. It is deeper in the tropics, up to 20 km, and shallower near the polar regions, approximately 7 km in winter. The lowest part of the troposphere, where friction with the Earth's surface influences air flow, is the planetary boundary layer. This layer is typically a few hundred meters to 2 km deep depending on the landform and time of day. The border between the troposphere and stratosphere, called the tropopause, is a temperature inversion.</span>
The beginning of cultivation is regarded as a landmark in the history of human progress because it provides opportunities to manage nature and the environment in return to earn their livelihoods.
<h3>What is Cultivation?</h3>
Cultivation may be defined as the process of preparing lands and growing crops by the farmers for the huge human population as well as animals. It is an agricultural practice.
The beginning of cultivation delivers an idea to humans through which they can sustain themselves by earning income. The activity of cultivation was initiated in the Neolithic age. Since then, it creates a lot of opportunities for farmers in order to make their progress.
Therefore, the alteration of foods from food products represents the initiation of cultivation that is considered a landmark in the history of human progress.
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a- an adult.
adult butterflies are constantly on the look out to reproduce - See more at: http://www.thebutterflysite.com/life-cycle.shtml#sthash.ZP0cJCO3.dpuf