Answer:
A. His frequent wars against Protestant and Muslims.
Step-by-step explanation:
Philip II was a fervent Catholic and it is true that he started many wars to defend the power and influence of the Catholic Church against Protestants and Muslims, but wars cost a lot of money and Philip has already inherited the throne with Spain bordering on bankruptcy. To pay for the wars, he had to borrow money from other nations, which caused a huge expenditure of money, leading to complete bankruptcy in 1598. It took a long period of reforms for Spain to have an efficient economy again.