Select the most appropriate synonym of the highlighted word.

The moral values in this nation were at their nadir during the autocrat’s rule.

base

The correct answer is option 3. base.

In the given sentence, the word "moral" refers to ethical principles or values. When it says "moral values in this nation were at their nadir," it means that the ethical standards or principles reached their lowest point or were at their worst during the autocrat's rule.

The synonym "base" can refer to the lowest part or foundation of something. In this context, it metaphorically indicates the lowest point or the foundation of moral values in the nation during the autocrat's rule. Therefore, "base" serves as an appropriate synonym for "moral" in this context.