Which of the following best matches the definition of "vivacious"?

The term "vivacious" describes someone who is lively, animated, and full of energy. It conveys a sense of enthusiasm and spiritedness, often associated with an engaging and appealing personality. This characteristic makes it synonymous with being vibrant and cheerful. Therefore, the choice that aligns with this definition—illustrating the essence of liveliness and energetic spirit—is the first option.

In contrast, the other options depict various states of being that are contrary to the lively essence of "vivacious." For example, being quiet and calm suggests a reserved or subdued demeanor, while being indifferent and casual indicates a lack of energetic engagement. Similarly, serious and solemn describes a state that is thoughtful and grave, which does not convey the same brightness and energy that "vivacious" embodies. Thus, the first choice stands out as the most fitting representation of the word.