Overcrowding and slums developed in many impoverished countries in the 20th century, mostly due to large migrations to cities from people looking for work.
Because the Moon<span> rotates </span>on<span> its axis at the same rate that the </span>Moon<span> orbits the </span>Earth<span>, </span>a<span> situation known as synchronous rotation or tidal locking. The </span>Moon is <span>directly illuminated by the Sun, and the cyclically varying viewing conditions cause the lunar phases.
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C is the answer both a and b
Answer:
Based on the solar light that enters the oceans and river
Explanation:
- River ecosystem of a couple of both biotic and abiotic components among the plants and animals involving there physical and chemical properties. As the flow of water is unidirectional, it's in state of continuous physical change and has a high degree of spatial and temporal heterogeneity.
- River sources are small, and in the areas of mountain streams, are steep and erosional. In temperate environments, overhead tree canopy conditions result in cool, well-oxygenated streams.
- All sorts of communities like coastal, estuaries, reefs and deep-sea trenches like Mariana trench which has no sunlight has a distinct type of community.
