The most important long-term impact of Socrates was

his training of the philosopher Plato.
the criminal activity that led to his death sentence.
his encouragement of good citizenship.
his promotion of critical thinking and reason.

The most important long-term impact of Socrates was his promotion of critical thinking and reason. Socrates believed in questioning and challenging commonly held beliefs and ideas, encouraging individuals to think for themselves and seek truth through rational inquiry. This emphasis on critical thinking and reasoning has had a lasting influence on Western philosophy, science, and education, shaping the way we approach knowledge, ethics, and problem-solving. Plato, one of Socrates' most famous students, continued his teacher's legacy by developing his own philosophical theories and founding the Academy, setting the stage for the systematic study of philosophy and the pursuit of knowledge.