Which one of the following statements best reflects the crux of the passage given above ?

Correct Option: (b) Any form of government tends to deteriorate by excess of its basic principle.

Passage 4 by Plato explains how different forms of government ruin themselves: aristocracy by narrowing power too much, oligarchy by scramble for wealth, and democracy by its own excess because the uneducated populace lacks understanding and merely repeats what rulers tell them, turning into tyranny. The underlying crux or recurring theme across all forms mentioned is that any form of government tends to deteriorate or ruin itself by the excess of its basic principle. Option (b) perfectly encapsulates this central thesis. Option (a) is a mere observation, option (c) focuses only on education, and option (d) misinterprets the text.