Which of the following form part of the borders of almost all central american countries ?
a. caribbean sea and mexico
b. caribbean sea and pacific ocean
c. north america and south america
d. pacific ocean and honduras

Caribbean Sea and Mexico form part of the borders of almost all Central American countries .
So it's A the right answer

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.