Final answer:
After the Act of Supremacy in 1534, the highest spiritual authority in England was the English monarch, with the Archbishop of Canterbury serving as the highest ecclesiastical authority.
Step-by-step explanation:
Following the Act of Supremacy in 1534, the highest spiritual authorities in England became the English monarchs themselves, starting with King Henry VIII who was declared the Supreme Head of the Church of England. The archbishop of Canterbury became the highest ecclesiastical authority under the monarch and was responsible for day-to-day spiritual governance, including the annulment of Henry VIII and Catherine of Aragon's marriage. This move essentially separated the English church from the authority of the Roman Catholic pope and established the Church of England (Anglican Church).