Municipal boundaries are used to A. mark the limits of city governments
B. divide states and group nearby cities
C. separate areas represented in the country's government
D. mark boundaries between countries

Answer carbon dioxide ice;

Magma forms by partial melting of upper mantle and crust. partial melt means that only a fraction of the available material forms a melt, and that the remainder stays solid. the partial melt rises because of its lower density and ascends through he crust. this is so conclusive mean the answer would be magma igneous rocks or balistic magma.