If you chose C, you're right! Though it took a trip through Italian and French before it landed in English, "trio" originates from the Latin "tri-," which means "three." You probably already know that if you are familiar with geometry and know that a triangle has three angles. ("Triangle" comes from the Latin words that mean "three angles.") English features some words that use either the Latin or Greek numerical root words, but the most common are math terms ("triangle," "polygon") or music terms ("duo," "quintet").