Final answer:
Philip II of Spain gained significant amounts of gold and silver from his New World colonies, which were essential resources that fuelled the Spanish economy and mercantilism. Hence, the correct answer is option A,
Step-by-step explanation:
One of the main resources that Philip II gained from his colonies in the New World was gold and silver. Spain's colonies in the Americas were incredibly valuable due to the vast amounts of precious metals they extracted, particularly from territories like New Spain and Peru.
These resources played a critical role in Spain's economy and the implementation of mercantilist policies, under which the colonies provided raw materials to Spain, which then turned them into finished goods to sell back to the colonies or elsewhere at a profit.