Final answer:
Basaltic magma is the most common type of magma that erupts from Earth's surface through volcanoes, leading to the formation of extrusive igneous rocks like basalt.
Step-by-step explanation:
The type of magma that most commonly erupts from the Earth's surface through volcanoes is d) Basaltic magma. Basaltic magma leads to the formation of extrusive igneous rocks, which cool quickly at the surface and are fine-grained lacking big crystals. In contrast, if magma stays within the Earth and cools over thousands of years it forms coarse-grained igneous rock such as plutonic or intrusive igneous rock, which appear 'sugary' due to their large crystals reflecting light.
Oceanic crust is predominantly made up of mafic magma, which, when erupted on the seafloor, forms basalt lava flows or cools to make intrusive igneous rock like gabbro. Not all volcanic eruptions form mountains; some produce vast lava plains like the Deccan plateau in India. Extrusive igneous rocks such as volcanic rocks can be seen as proof of such eruptions.