What does the verb "impugn" mean?

The verb "impugn" specifically means to attack or challenge someone's character or statements, often by suggesting that they are false or wrong. This word is frequently used in contexts where someone's credibility or the validity of their arguments is being questioned. For example, one might impugn a politician's statements if they believe they are misleading or dishonest.

The other options refer to different actions or concepts that do not align with the meaning of "impugn." The first choice speaks to growth in favorable conditions, which is unrelated; the third choice involves enthusiastic action, a concept that does not connect to the idea of challenging or disputing something; and the fourth choice suggests a subtle introduction, which is again completely distinct from the notion of attacking someone's integrity or honesty. Therefore, the correct answer encapsulates the essence of challenging the truthfulness of information or a person's integrity.