Final answer:
A volcano erupting gassy, felsic magma is more likely to result in an explosive eruption due to the higher viscosity and gas content of the magma, causing more pressure and violent eruptions.
Step-by-step explanation:
If a volcano is erupting a gassy, felsic magma, then it is more likely to be an explosive eruption. Felsic magmas generally have high viscosity and higher gas content, which results in a greater buildup of pressure, leading to violent eruptions. An example of this type of eruption was the violent explosion of Mount Vesuvius. In contrast, effusive eruptions involve magma that is more mafic and less viscous, allowing gases to escape more easily, resulting in lava flows rather than explosive activity.