Which of the following is an example of how a changing environment is important for the sustainability of living systems?   a.  the water cycle ensures that water used by one organism will be available for another organism in the future.  b.  the erosion of top soil reduces the diversity of organisms in an ecosystem.  c.  global climate change may lead to the extinction of many species that are unable to adapt to the changes.  d.  all of these

A.  The water cycle ensures that water used by one organism will be available for another organism in the future.

Explanation:

Water is a crucial substance for life on earth. The water cycle is extremely important for the sustainability of living systems, because it collects, purifies and distributes the fixed amount of water on the planet. Through the water cycle the water used by one organism will be available to another organism in the future.

The water cycle is powered by the sun's energy and involves three major processes: evaporation, precipitation and transpiration. Solar radiation causes evaporation of water contained in oceans, lakes, rivers and soil. Evaporation transforms liquid water to water vapor, and later gravity causes water to return to the earth's surface as precipitation. On land, 90% of the water that reaches the atmosphere evaporates from the plant surface through the process of evapotranspiration and from the soil.

Water that returns to the earth's surface as precipitation follows different paths. Most of the precipitation that occurs on terrestrial ecosystems flows superficially and gathers to form rivers and streams. Some of this surface water seeps into the upper layers of the soil and is used by plants and some of it evaporates from the soil into the atmosphere. Some precipitation is converted to ice and stored in glaciers, usually after long periods of time. Some precipitation seeps into the soil and permeable rocks and is stored as groundwater in geological formations called aquifers. A small portion of the water is used by living things.

he is very short, and he can only reach halfway up on the elevator buttons. but on a rainy day, he has his umbrella with him, and he uses it to poke the button at the top.