Choose the true statement. a. when earth gets hotter, ice caps melt and sea levels drop. b. earth has had very few changes in climate over its long history. c. when earth gets cooler, more water freezes and sea levels rise. d. studying fossils us better understand earth's environmental and geological histories.

Answer volcanic eruptionsseismic waves from earthquakes;

The us is first  the  u.s. economy  remains the  largest in the world  in terms of nominal  gdp. however, the  u.s. economy  loses its spot as the number one  economy  to china when  measured  in terms of  gdp  based on ppp. in these terms, china's  gdp  is $23.19 trillion exceeds the  u.s. gdp  of $19.42 trillion