Your friend is wary of environmentalists' claims that global warming could lead to major biological change on Earth. Which of the following statements can you use in response to your friend's suspicions? a. Many plants and animals are susceptible to slight changes in their local environments.
b. All answer choices are correct. Global warming could have significant effects on agriculture in the United States, upon which many American rely for income.
c. We can observe evidence that atmospheric carbon dioxide has increased over the past 150 years.
d. Through measurements and observations, we know that carbon dioxide levels and temperature fluctuations are directly correlated, even in prehistoric times.

The correct statement used in response to the suspicions should contain all the statements, therefore all answer choices are correct. (a, b, c, and d).

Explanation:

Global warming is an environmental situation in which there is an abnormal rise in temperature around the world due to increase in carbondioxide and other greenhouse gases such as carbon monoxide,chlorofluorocarbons, nitrogen oxides and lead.

The consequences that may emerge due to the global warming includes'

--> Reduction in biodiversity: atmospheric changes in the environment can cause mass extinction of plants and animal species that cannot migrate to new areas. Therefore option A is correct.

--> change in food production: Current climate models project 10 - 70% decline in the global yield of key food crop and a loss in current crop land area of which United States is not an exception. Therefore option B is correct.

--> Increase in atmospheric carbondioxide: this is as a result of Increased dependency on fossil fuels for energy production. Option C is correct.

--> Greenhouse effect: the unabsorbed carbondioxide becomes traped in the upper atmosphere preventing the radiation of solar energy back into the space. This leads to an increase in the global temperature which is called greenhouse effect. Therefore option D is correct.

1) a giant star is a star with a radius much larger than that of our sun (even hundreds of times bigger). they can be either blue giants or red giants: in the first case, the surface temperature is very high, higher than that of the sun, while in the second case the surface temperature can be lower than that of the sun. the same applies to the mass: blue giants are very massive stars, burning quickly their nuclear fuel, while red giants can have small masses (a little bit bigger than that of our sun).

2) we can find giant stars in the upper part of the hr diagram, blue giants will be on the upper left corner since they have high luminosity and high temperature, while red giants will be on the upper right corner, having high luminosity but low temperature.