Answer:
B. A sort of musical shorthand.
Step-by-step explanation:
Figured Bass is an alternate technique for harmonic notation originating in the Baroque Era, also known as Through Bass or Bass Continuo. In Figured Bass instead of writing chord symbols like we do today, you would provide a written base line with markings below to indicate which intervals above that bass note are acceptable within the harmony.
Using this sort of musical shorthand gives you a completely different way to think about harmony. In Figured Bass compositions, the actual structure of the bass line is important with more smooth steps and voice leading and almost serving as another melody at times and inversions pop up way more often. The primary job of Figured Base Notation is to tell you which chord tone the bass note is.