What magma property most directly dictates a volcano’s explosive eruption style?

💡 Explanation:

The explosiveness of a volcanic eruption is primarily dictated by the magma's viscosity. High viscosity, typically associated with high-silica (felsic/intermediate) magma, prevents dissolved gases from escaping easily. This gas entrapment leads to a rapid and massive pressure build-up within the magma chamber, culminating in a violent, explosive eruption, characteristic of stratovolcanoes.