Your intellect is a lively one if you chose C! "Vivacious," "lively," and "sprightly" all mean very alive and spirited. "Vivacious" suggests an active wittiness that is often playful or attractive (as in, "a vivacious talk-show host"). "Lively" implies alertness, quickness, or energy (such as, "politicians engaged in a lively debate about foreign policy"). "Sprightly" is used of something or someone light and playful that enjoys or revels in life (for example, "sprightly, upbeat music that had us all out on the dance floor").