Answer:
1 migration
2 the northern regions have become warm
C I think would be the best answer for this question!
Answer:
planetesimal is (astronomy) any of many small, solid astronomical objects, that orbit a star and form protoplanets through mutual gravitational attraction while planet is (astronomy) a body which orbits the sun directly and is massive enough to be in hydrostatic equilibrium (effectively meaning a spheroid)
Answer:
Blood flows from the right atrium into the right ventricle through the open tricuspid valve, and from the left atrium into the left ventricle through the open mitral valve
