Answer:
The correct answer is a.
Step-by-step explanation:
The explosive reaction depends on the amount of gas dissolved in the magma and its viscosity.
Low-viscosity magmas allow gases to easily escape to the surface, reducing the likelihood of an explosive release. While high viscosity magnets retain the gases and increase the pressure producing a greater probability of an explosive release occurring.
This magma when it reaches high pressures and when it overcomes the resistance it encounters, escapes violently, giving rise to an explosive eruption.
Have a nice day!