Final answer:
Antoine-Joseph Sax invented the saxophone in 1842 as a way to improve the sound of the bass clarinet.
Step-by-step explanation:
Antoine-Joseph Sax invented the saxophone in 1842 as a way to improve the sound of the bass clarinet. The saxophone was first exhibited by Sax himself, showcasing his invention to the public. Therefore, option B. he invented it is the correct choice.