Final answer:
Magma, studied by volcanologists, comes from the asthenosphere, a layer of Earth's interior associated with volcanic activity.
Step-by-step explanation:
A volcanologist studies magma, which originates from the Earth's interior. Magma is formed in the mantle and can rise through the crust to erupt as lava from volcanoes. Although several layers make up the Earth's interior, the layer directly associated with the generation and rise of magma due to temperature increases and melting rock is the asthenosphere. This layer lies beneath the lithosphere and is involved in plate tectonics and mantle convection, influencing the creation of many geological features such as mountains, valleys, and volcanoes.
In answer to the student's question: Magma comes from the Earth's interior in the D. Asthenosphere.