Much like a cell, a virus is able to

a. obtain and use energy. b. grow and develop. c. change over time. d. respond to its environment.

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.