Savannas do not exist in the united states

Savannas do not exist in the US because there are no true tropic climates.

Ithink the answer to that would be b):

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.