Final answer:
Gustavus Adolphus, King of Sweden, was the important Protestant leader who died in battle in 1632 during the Thirty Years' War, making the correct answer B. Gustavus Adolphus.
Step-by-step explanation:
The important leader of the Protestant forces during the war who perished on the battlefield in 1632 was B. Gustavus Adolphus. Gustavus Adolphus, the King of Sweden, played a pivotal role in the Thirty Years' War, leading the Swedish army against the Catholic Habsburgs in support of the Protestant cause. His death at the Battle of Lützen marked a significant point in the history of the conflict. In contrast, Oliver Cromwell was a leader during the English Civil War, not the Thirty Years' War. Philip II of Spain was an adversary of Protestantism, having attempted to reassert Catholic dominance in England with the Spanish Armada, and Henry IV of France had been assassinated earlier, in 1610.
Gustavus Adolphus was an important leader of the Protestant forces who died in 1632.The important leader of the Protestant forces who perished on the battlefield in 1632 was Gustavus Adolphus.