Magnetic Effects of Current and Magnetism Part 3

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R
Assertion A: If Oxygen ion ( O−2 ) and Hydrogen ion (H+)enter normal to the magnetic field with equal momentum, then the path of O−2 ion has a smaller curvature than that of H+.
Reason R: A proton with same linear momentum as an electron will form a path of smaller radius of curvature on entering a uniform magnetic field perpendicularly.
In the light of the above statements, choose the correct answer from the options given below