Final answer:
The quote by Ronald Reagan means authoritarianism undermines freedom by suggesting that concentrated power is a threat to liberty. Liberty is best safeguarded in a system with checks and balances to prevent any one entity from gaining excessive control.
Step-by-step explanation:
The quote "Concentrated power has always been the enemy of liberty," by Ronald Reagan, suggests that when power is concentrated in the hands of a few, it poses a threat to individual freedoms and liberties. The correct interpretation would be that authoritarianism undermines freedom (option a), which is the notion that extensive government control and a lack of civil rights and liberties are detrimental to the concept of liberty as embraced in democratic societies.
Governments that exercise too much control, or tyranny, infringe on people’s rights and are considered dangerous according to many historical observations and political theories. This is exemplified by the reference to authoritarian governments, including monarchies, where power is usually centralized and citizens have limited freedoms. Moreover, warnings about the corrupting influence of power, as noted by Lord Acton, emphasize the necessity of limiting and controlling governmental power to protect liberty.
Liberty is best protected in a republican government where different branches and a system of checks and balances prevent any single entity from gaining too much control. The founders of the United States designed the government with these precautions in mind to ensure individual rights and prevent the majority from oppressing the minority.