For the first question, the answer is b. Federalism. This principle describes a system where power is shared between the national and state governments, both of which have authority over the same people and geographical area.
For the second question, the answer is d. Separation of Powers. John Adams is expressing the concern that concentrating all governmental powers in one assembly could threaten freedom and happiness, which aligns with the principle of separating legislative, executive, and judicial powers within the government.