How are fossils used to study past enviornments

Which of the following does not determine the type of magma to erupt from a volcano? a. temperature b. gas content c. viscosity d. silica content what kind of volcano forms from basaltic magma with low-viscosity and low-gas content? a. shield volcano b. stratovolcano c. composite-cone volcano d. cinder-cone volcano what is viscosity? a. a rising mass of mantle abnormally hot and / or wet b. a pool of magma beneath the overlying crust c. what causes a bend to occur in the rock layer d. a measure of a fluid's resistance to flow