The Book States That the Medieval Guild Was an Integral

The book states that the medieval guild was an integral part of feudalism. What was a medieval guild?

A) a group of employees join an organization which then bargains on their behalf with management over wages and working conditions.
B) A group of skilled craftsmen join an organization which establishes standards in their craft and sets prices.
C) a group of feudal lords join together to wage wars on behalf of the monarchy.
D) a group of merchants join together to generally promote business and commercial activities in a city or town.