What kind of emotion does "rue" encompass?

The term "rue" specifically refers to a feeling of deep regret or sorrow, often associated with sadness stemming from a sense of loss or missed opportunities. This emotion encompasses the notion of looking back on one's actions or decisions with a sense of remorse and wishing that different choices could have been made. It highlights the emotional weight of regret, where one feels a poignant sense of sadness related to past decisions or events that cannot be changed.

The other options do not align with the definition of "rue." Joy, indifference, and happiness from accomplishment reflect positive emotions or a lack of emotional engagement, which contrasts sharply with the essence of rue as a sorrowful recognition of regret. Thus, the connection of "rue" to sadness associated with regret makes choice B the most accurate representation of the term's meaning.