What creates the van allen belts
a. earths gravity
b. deflection of charged particles
c. aurora borealis
d. convection in the mantel?

b. deflection of charged particles  

Explanation:

The Van Allen Belt is a region where various atmospheric phenomena occur due to deflection of charged particles in the Earth's magnetic field, discovered in 1958 by James Van Allen, who designed a cosmic ray experiment embarked on the American explorer spacecraft Explorer 1, launched in January 2000. 1958. Van Allen's radiations do not occur, except for rare exceptions, at the poles, but in the equatorial region. These form two ring-shaped belts, centered on the equator.  The innermost reaches between altitudes of one thousand and five thousand kilometers, its maximum intensity occurring on average at three thousand kilometers. It consists of highly energetic protons, which originate from the decay of neutrons produced when cosmic rays from outer space collide with atoms and molecules of the earth's atmosphere. Some of the neutrons are ejected out of the atmosphere and disintegrate into protons and electrons as they cross this region of the belt. These particles move in spiral trajectories along force lines of the earth's magnetic field.

The atomic radius of main group elements generally increases down a group because as there are more electrons they are farther away from the nucleus and the electrons closer to the nucleus shield the outer electrons from the protons for attraction.