Recap:Why does magma viscosity predict volcano explosivity?

Recap: Why does magma viscosity predict volcano explosivity? 

Select one:

a. Low viscosity magma is more easily expelled from the vent.

b. 

c. 

d. When the gases boil, the vapor moves lava into the air as hot ash—in the same way that an aerosol spray can disperses a fluid (e.g., hairspray). 

e.