Final answer:
The intensity of cosmic rays is largest at the polar regions because Earth's magnetic field allows more direct access to the atmosphere than at the equator, tropics, or high altitudes like Mount Everest.
Step-by-step explanation:
The intensity of cosmic rays bombarding the Earth's surface varies with geographic location, largely due to Earth's magnetic field. Cosmic rays that approach the Earth near the equator have to cross more of the Earth's magnetic field lines, which can deflect and prevent many from penetrating the atmosphere.
In contrast, at the poles, Earth's magnetic field lines converge and are more vertically oriented, allowing cosmic rays to enter the atmosphere more directly. Therefore, the intensity of cosmic rays is larger at the polar regions compared to the equator, tropics, or even high altitudes such as Mount Everest.