Modesty is chaste in both ________ and conduct.

The concept of modesty encompasses a sense of humility and decency that reflects in both internal and external aspects of a person's life. The correct answer highlights that modesty is chaste in both thought and conduct, indicating that it involves maintaining pure and respectful thoughts while also demonstrating appropriate behavior.

By emphasizing the mind alongside actions, this choice conveys the importance of having a wholesome mindset that aligns with virtuous behavior. Essentially, modesty is not just about how one presents themselves externally, but also about the internal values and attitudes that guide their behavior. This comprehensive understanding underlines the belief that true modesty starts from within.

Other options, while relevant in their own ways, do not capture the duality implied in the question as effectively as thought does. For instance, modesty in appearance refers mainly to external presentation, and while attitude and emotion relate to personal feelings and expressions, they may not encapsulate the aspect of purity in thought which is integral to the complete definition of modesty.