according to plate tectonics, the continents__ . A ; do not move at all . B ; are drifting on a sea of magma . C ; will one day be joined together . D ; “float” on top of the crust .

a polymer is a chainlike molecule made up of small molecular units. these small molecular units are called monomers. monomers of polymer can be joined together either naturally or synthetically.  

volcanoes (an event in the geosphere) release a large amount of particulate matter into the atmosphere. these particles serve as nuclei for the formation of water droplets (hydrosphere). rainfall (hydrosphere) often increases following an eruption, stimulating plant growth (biosphere).

well, i believe that the answer is 2. : 3