Final answer:
The timpani is the instrument primarily responsible for supplying rhythmic energy in the Classical orchestra.
Step-by-step explanation:
In the Classical orchestra, the instrument primarily responsible for supplying rhythmic energy is the timpani. The timpani, also known as kettledrums, are a set of large drums that are tuned to specific pitches and played with mallets. They provide a strong and steady beat, adding rhythmic intensity to the music.