Continuing my tips for beginner clarinets:
C is for CLARINET! Of course!
It is also for "Clarion" and Chalumeau: names for two of the clarinet registers.
Chalumeau is the name of the instrument our modern clarinet descended from. In 1690, Johann Christof Denner added the "register key", and a whole new range was born. The Chalumeau register is the lowest register on the clarinet. (Low E to first space F)
Clarion refers to the new, higher register (middle line B to high C), which is simply the chalumeau fingerings with the register key depressed as well. It is the middle range.