Final answer:
Guy of Lusignan led the Siege of Acre and was the King of Jerusalem, a title he gained through marriage to Queen Sibylla. The correct option is B.
Step-by-step explanation:
The question is asking about Guy of Lusignan and the particular siege he led. Guy of Lusignan led the Siege of Acre, and he had the title of King of Jerusalem.
The reason for him leading the siege was because of the historical events surrounding the Crusades, specifically the third one.
Guy was made King of Jerusalem through his marital connection to Sibylla, the sister of the previous king, Baldwin IV.
This connection came about after a series of complex political maneuvers and inheritances amongst the European nobility in the crusader states. The correct option is B.