Answer:
d. fought Frederick Barbarossa.
Step-by-step explanation:
The Lombard League was a group of city-states in northern Italy that united to fight against the Holy Roman Emperor, Frederick Barbarossa, during the 12th century. The League was formed in 1167 in response to the Emperor's attempts to expand his power and control over the independent city-states of northern Italy. The League, which was primarily made up of cities such as Milan, Venice, and Florence, was able to successfully resist the Emperor's attempts to conquer them, and eventually forced him to recognize their autonomy and independence.