A

Step 1: Understand the nature of cosmic rays. Cosmic rays are charged particles, mostly protons, originating from outer space.
Step 2: When these charged particles enter the Earth's atmosphere, they are affected by the Earth's magnetic field.
Step 3: The Earth's magnetic field deflects positively charged particles in a direction dependent on their charge and the orientation of the magnetic field. In general, positively charged particles are deflected towards the east in the northern hemisphere.
Step 4: Based on this understanding, the cosmic rays falling down are predominantly deflected towards the east.
Conclusion: Therefore, the correct answer is A.