The correct answer is- Proton
A proton is approximately 2,000 times heavier than an electron. In most cases, atoms have an equal number of protons and electrons. However, because protons are so much heavier than electrons, the electrons do not make a significant contribution to the mass of an atom.
I would say the answer would be D)
because back then in the 20’s it was politically correct and acceptable to target particular ethnic groups from being able to migrate to your country.
All of the other immigration acts have occurred within the last 50 years or so when it would NOT be acceptable to enforce this kind of exclusion.
hope this helps!