What are the primary factors that determine whether a volcano erupts explosively or relitivly quietly.

Chemical composition,temperature, viscosity
different chemicals in an erupting volcano's magma affects the temperature, which in turn affects the viscosity, which affects the eruption itself
for example, less silica content in the magma means lower temperature which means the lava cools down faster and hardens faster, which means the viscosity increases, which in turn results in  relatively quiet explosion.

Answer:

1: the largest region of the brain is the:

  cerebrum

2. the term "psychology" literally means:

the process or procedure of the science or study of the mind.

3. the area of the brain responsible for respiration, heart rate, and smooth muscle control of our blood vessels is t

medulla oblongata

4. the structure that conducts nerve impulses to and from the brain and serves as a reflex center for some sensory information without input from the brain is the:

spinal cord

5. the three-layered membrane that covers the brain and spinal cord and literally means membrane is called the:

meninges

6. the cord-like (string-like) structures that carry bio-electrical impulses from one part of the body to another are called

nerves

7. a group of nerve cell bodies that are found outside of the spinal cord and brain are referred to as:

ganglions or ganglia (pl.) “literal meaning knot”

8. the term that means spinal cord inflammation is:

myel/itis

The answer is d have a nice day