Final answer:
Frederick I, also known as Frederick Barbarossa, led his army out of Germany to participate in the Third Crusade in the year 1189, which makes the correct answer to the student's question option B) 1189.
Step-by-step explanation:
The student is asking about a historical event related to Frederick I, also known as Frederick Barbarossa, who was the Holy Roman Emperor during the time of the Third Crusade. Concerning the options provided to the question of when Frederick's army marched out of Germany, we refer to the historical period of the crusades, specifically the Third Crusade which took place between the years 1189 and 1191.
According to historical records, the Third Crusade began after the fall of Jerusalem in 1187, and European leaders including Frederick Barbarossa, Richard the Lionheart of England, and Philip II of France took the cross to retake the Holy Land from Saladin. Frederick Barbarossa embarked on his campaign and marched out of Germany in the year 1189, leading a massive army towards the Holy Land. Therefore, the correct answer to the student's question would be option B) 1189.