The correct answers are:
- land formation;
- fertile soil;
- geothermal energy;
- construction materials;
The volcanic activity can be seen in two ways, the negative, hazardous nature of them, and the positive, beneficial nature of them. While there's multiple volcanic hazards that we are familiar with, there's also multiple benefits from the volcanoes. Some of the benefits are the land formation, fertilizing the soil, geothermal energy, construction materials.
The volcanoes very often form as islands, thus they create new spaces of land.
With the volcanic eruptions, lot of material is released, one of them being the ash, and by producing lots of ash which falls on the land, the volcanoes are fertilizing the soil.
The geothermal energy is a found in close proximity to the volcanoes, and it attractive and beneficial for the humans for tourism and as a renewable energy source.
Most of the construction materials need to very strong, and the strongest materials come from the cooling lava from the volcanoes, thus providing the humans with the necessary high quality construction materials.