English Police Officers Are Known as Bobbies Because

English police officers are known as bobbies because:

A) their heads often bobbed up and down as they rode the streets of London on horses.
B) Sir Robert (Bobbie) Peel was responsible for their creation.
C) an inordinately large number of the original London metropolitan police force was named Bobbie.
D) they are trained to bob their head whenever a member of the royal family came into view.