Which of these statements about the atmosphere is correct?
(Mark the one best answer.)
O A The amount of each gas in the atinosphere is fixed and cannot change.
OB The amounts of greenhouse gases in the atmosphere can change.
O C Most gases in the atmosphere are greenhouse gases,
OD Most gases in the atmosphere are required for animal life.

Many organizations release indexes used to measure the development of the world's countries. as we learned in this lesson, these indexes measure many factors, from life expectancy to happiness. in your opinion, what are the three most important factors we can use to determine how developed a country might be? explain your answers in a few sentences.